Commit message: mm, uprobes: fix multiple free of ->uprobes_state.xol_area

Commit 7c051267931a ("mm, fork: make dup_mmap wait for mmap_sem for
write killable") made it possible to kill a forking task while it is
waiting to acquire its ->mmap_sem for write, in dup_mmap().

However, it was overlooked that this introduced an new error path before
the new mm_struct's ->uprobes_state.xol_area has been set to NULL after
being copied from the old mm_struct by the memcpy in dup_mm().  For a
task that has previously hit a uprobe tracepoint, this resulted in the
'struct xol_area' being freed multiple times if the task was killed at
just the right time while forking.

Fix it by setting ->uprobes_state.xol_area to NULL in mm_init() rather
than in uprobe_dup_mmap().

With CONFIG_UPROBE_EVENTS=y, the bug can be reproduced by the same C
program given by commit 2b7e8665b4ff ("fork: fix incorrect fput of
->exe_file causing use-after-free"), provided that a uprobe tracepoint
has been set on the fork_thread() function.  For example:

    $ gcc reproducer.c -o reproducer -lpthread
    $ nm reproducer | grep fork_thread
    0000000000400719 t fork_thread
    $ echo "p $PWD/reproducer:0x719" > /sys/kernel/debug/tracing/uprobe_events
    $ echo 1 > /sys/kernel/debug/tracing/events/uprobes/enable
    $ ./reproducer

Here is the use-after-free reported by KASAN:

    BUG: KASAN: use-after-free in uprobe_clear_state+0x1c4/0x200
    Read of size 8 at addr ffff8800320a8b88 by task reproducer/198

    CPU: 1 PID: 198 Comm: reproducer Not tainted 4.13.0-rc7-00015-g36fde05f3fb5 #255
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-20170228_101828-anatol 04/01/2014
    Call Trace:
     dump_stack+0xdb/0x185
     print_address_description+0x7e/0x290
     kasan_report+0x23b/0x350
     __asan_report_load8_noabort+0x19/0x20
     uprobe_clear_state+0x1c4/0x200
     mmput+0xd6/0x360
     do_exit+0x740/0x1670
     do_group_exit+0x13f/0x380
     get_signal+0x597/0x17d0
     do_signal+0x99/0x1df0
     exit_to_usermode_loop+0x166/0x1e0
     syscall_return_slowpath+0x258/0x2c0
     entry_SYSCALL_64_fastpath+0xbc/0xbe

    ...

    Allocated by task 199:
     save_stack_trace+0x1b/0x20
     kasan_kmalloc+0xfc/0x180
     kmem_cache_alloc_trace+0xf3/0x330
     __create_xol_area+0x10f/0x780
     uprobe_notify_resume+0x1674/0x2210
     exit_to_usermode_loop+0x150/0x1e0
     prepare_exit_to_usermode+0x14b/0x180
     retint_user+0x8/0x20

    Freed by task 199:
     save_stack_trace+0x1b/0x20
     kasan_slab_free+0xa8/0x1a0
     kfree+0xba/0x210
     uprobe_clear_state+0x151/0x200
     mmput+0xd6/0x360
     copy_process.part.8+0x605f/0x65d0
     _do_fork+0x1a5/0xbd0
     SyS_clone+0x19/0x20
     do_syscall_64+0x22f/0x660
     return_from_SYSCALL_64+0x0/0x7a

Note: without KASAN, you may instead see a "Bad page state" message, or
simply a general protection fault.

Link: http://lkml.kernel.org/r/20170830033303.17927-1-ebiggers3@gmail.com
Fixes: 7c051267931a ("mm, fork: make dup_mmap wait for mmap_sem for write killable")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reported-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>    [4.7+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
CVE: CVE-2017-17052
CWE: CWE-416
Vulnerability description: The mm_init function in kernel/fork.c in the Linux kernel before 4.12.10 does not clear the ->exe_file member of a new process's mm_struct, allowing a local attacker to achieve a use-after-free or possibly have unspecified other impact by running a specially crafted program.

Project: linux
File: uprobes.c

void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end)
{
	if (no_uprobe_events() || !valid_vma(vma, false))
		return;

	if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */
		return;

	if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) ||
	     test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags))
		return;

	if (vma_has_uprobes(vma, start, end))
		set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags);
}

Project: linux
File: uprobes.c

find_node_in_range(struct inode *inode, loff_t min, loff_t max)
{
	struct rb_node *n = uprobes_tree.rb_node;

	while (n) {
		struct uprobe *u = rb_entry(n, struct uprobe, rb_node);

		if (inode < u->inode) {
			n = n->rb_left;
		} else if (inode > u->inode) {
			n = n->rb_right;
		} else {
			if (max < u->offset)
				n = n->rb_left;
			else if (min > u->offset)
				n = n->rb_right;
			else
				break;
		}
	}

	return n;
}

Project: linux
File: uprobes.c

static struct uprobe *__insert_uprobe(struct uprobe *uprobe)
{
	struct rb_node **p = &uprobes_tree.rb_node;
	struct rb_node *parent = NULL;
	struct uprobe *u;
	int match;

	while (*p) {
		parent = *p;
		u = rb_entry(parent, struct uprobe, rb_node);
		match = match_uprobe(uprobe, u);
		if (!match)
			return get_uprobe(u);

		if (match < 0)
			p = &parent->rb_left;
		else
			p = &parent->rb_right;

	}

	u = NULL;
	rb_link_node(&uprobe->rb_node, parent, p);
	rb_insert_color(&uprobe->rb_node, &uprobes_tree);
	/* get access + creation ref */
	atomic_set(&uprobe->ref, 2);

	return u;
}

Project: linux
File: uprobes.c

static struct uprobe *insert_uprobe(struct uprobe *uprobe)
{
	struct uprobe *u;

	spin_lock(&uprobes_treelock);
	u = __insert_uprobe(uprobe);
	spin_unlock(&uprobes_treelock);

	return u;
}

Project: linux
File: fork.c

static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
	struct user_namespace *user_ns)
{
	mm->mmap = NULL;
	mm->mm_rb = RB_ROOT;
	mm->vmacache_seqnum = 0;
	atomic_set(&mm->mm_users, 1);
	atomic_set(&mm->mm_count, 1);
	init_rwsem(&mm->mmap_sem);
	INIT_LIST_HEAD(&mm->mmlist);
	mm->core_state = NULL;
	atomic_long_set(&mm->nr_ptes, 0);
	mm_nr_pmds_init(mm);
	mm->map_count = 0;
	mm->locked_vm = 0;
	mm->pinned_vm = 0;
	memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
	spin_lock_init(&mm->page_table_lock);
	mm_init_cpumask(mm);
	mm_init_aio(mm);
	mm_init_owner(mm, p);
	RCU_INIT_POINTER(mm->exe_file, NULL);
	mmu_notifier_mm_init(mm);
	init_tlb_flush_pending(mm);
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
	mm->pmd_huge_pte = NULL;
#endif
	mm_init_uprobes_state(mm);

	if (current->mm) {
		mm->flags = current->mm->flags & MMF_INIT_MASK;
		mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
	} else {
		mm->flags = default_dump_filter;
		mm->def_flags = 0;
	}

	if (mm_alloc_pgd(mm))
		goto fail_nopgd;

	if (init_new_context(p, mm))
		goto fail_nocontext;

	mm->user_ns = get_user_ns(user_ns);
	return mm;

fail_nocontext:
	mm_free_pgd(mm);
fail_nopgd:
	free_mm(mm);
	return NULL;
}

Project: linux
File: uprobes.c

int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)
{
	return uprobe_write_opcode(mm, vaddr, UPROBE_SWBP_INSN);
}

Project: linux
File: uprobes.c

remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr)
{
	set_bit(MMF_RECALC_UPROBES, &mm->flags);
	return set_orig_insn(&uprobe->arch, mm, vaddr);
}

Project: linux
File: uprobes.c

unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs)
{
	return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE;
}

Project: linux
File: uprobes.c

handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs)
{
	struct uprobe *uprobe = ri->uprobe;
	struct uprobe_consumer *uc;

	down_read(&uprobe->register_rwsem);
	for (uc = uprobe->consumers; uc; uc = uc->next) {
		if (uc->ret_handler)
			uc->ret_handler(uc, ri->func, regs);
	}
	up_read(&uprobe->register_rwsem);
}

Project: linux
File: uprobes.c

static bool valid_vma(struct vm_area_struct *vma, bool is_register)
{
	vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_MAYSHARE;

	if (is_register)
		flags |= VM_WRITE;

	return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC;
}

Project: linux
File: uprobes.c

static void mmf_recalc_uprobes(struct mm_struct *mm)
{
	struct vm_area_struct *vma;

	for (vma = mm->mmap; vma; vma = vma->vm_next) {
		if (!valid_vma(vma, false))
			continue;
		/*
		 * This is not strictly accurate, we can race with
		 * uprobe_unregister() and see the already removed
		 * uprobe if delete_uprobe() was not yet called.
		 * Or this uprobe can be filtered out.
		 */
		if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end))
			return;
	}

	clear_bit(MMF_HAS_UPROBES, &mm->flags);
}

Project: linux
File: uprobes.c

static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode)
{
	uprobe_opcode_t old_opcode;
	bool is_swbp;

	/*
	 * Note: We only check if the old_opcode is UPROBE_SWBP_INSN here.
	 * We do not check if it is any other 'trap variant' which could
	 * be conditional trap instruction such as the one powerpc supports.
	 *
	 * The logic is that we do not care if the underlying instruction
	 * is a trap variant; uprobes always wins over any other (gdb)
	 * breakpoint.
	 */
	copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE);
	is_swbp = is_swbp_insn(&old_opcode);

	if (is_swbp_insn(new_opcode)) {
		if (is_swbp)		/* register: already installed? */
			return 0;
	} else {
		if (!is_swbp)		/* unregister: was it changed by us? */
			return 0;
	}

	return 1;
}

Project: linux
File: uprobes.c

int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr,
			uprobe_opcode_t opcode)
{
	struct page *old_page, *new_page;
	struct vm_area_struct *vma;
	int ret;

retry:
	/* Read the page with vaddr into memory */
	ret = get_user_pages_remote(NULL, mm, vaddr, 1,
			FOLL_FORCE | FOLL_SPLIT, &old_page, &vma, NULL);
	if (ret <= 0)
		return ret;

	ret = verify_opcode(old_page, vaddr, &opcode);
	if (ret <= 0)
		goto put_old;

	ret = anon_vma_prepare(vma);
	if (ret)
		goto put_old;

	ret = -ENOMEM;
	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
	if (!new_page)
		goto put_old;

	__SetPageUptodate(new_page);
	copy_highpage(new_page, old_page);
	copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);

	ret = __replace_page(vma, vaddr, old_page, new_page);
	put_page(new_page);
put_old:
	put_page(old_page);

	if (unlikely(ret == -EAGAIN))
		goto retry;
	return ret;
}

Project: linux
File: fork.c

int unshare_files(struct files_struct **displaced)
{
	struct task_struct *task = current;
	struct files_struct *copy = NULL;
	int error;

	error = unshare_fd(CLONE_FILES, &copy);
	if (error || !copy) {
		*displaced = NULL;
		return error;
	}
	*displaced = task->files;
	task_lock(task);
	task->files = copy;
	task_unlock(task);
	return 0;
}

Project: linux
File: uprobes.c

int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
{
	struct uprobe *uprobe;
	int ret;

	/* Uprobe must have at least one set consumer */
	if (!uc->handler && !uc->ret_handler)
		return -EINVAL;

	/* copy_insn() uses read_mapping_page() or shmem_read_mapping_page() */
	if (!inode->i_mapping->a_ops->readpage && !shmem_mapping(inode->i_mapping))
		return -EIO;
	/* Racy, just to catch the obvious mistakes */
	if (offset > i_size_read(inode))
		return -EINVAL;

 retry:
	uprobe = alloc_uprobe(inode, offset);
	if (!uprobe)
		return -ENOMEM;
	/*
	 * We can race with uprobe_unregister()->delete_uprobe().
	 * Check uprobe_is_active() and retry if it is false.
	 */
	down_write(&uprobe->register_rwsem);
	ret = -EAGAIN;
	if (likely(uprobe_is_active(uprobe))) {
		ret = __uprobe_register(uprobe, uc);
		if (ret)
			__uprobe_unregister(uprobe, uc);
	}
	up_write(&uprobe->register_rwsem);
	put_uprobe(uprobe);

	if (unlikely(ret == -EAGAIN))
		goto retry;
	return ret;
}

Project: linux
File: uprobes.c

static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
{
	int err;

	if (WARN_ON(!consumer_del(uprobe, uc)))
		return;

	err = register_for_each_vma(uprobe, NULL);
	/* TODO : cant unregister? schedule a worker thread */
	if (!uprobe->consumers && !err)
		delete_uprobe(uprobe);
}

Project: linux
File: uprobes.c

static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask)
{
	struct uprobe_task *n_utask;
	struct return_instance **p, *o, *n;

	n_utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL);
	if (!n_utask)
		return -ENOMEM;
	t->utask = n_utask;

	p = &n_utask->return_instances;
	for (o = o_utask->return_instances; o; o = o->next) {
		n = kmalloc(sizeof(struct return_instance), GFP_KERNEL);
		if (!n)
			return -ENOMEM;

		*n = *o;
		get_uprobe(n->uprobe);
		n->next = NULL;

		*p = n;
		p = &n->next;
		n_utask->depth++;
	}

	return 0;
}

Project: linux
File: uprobes.c

register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new)
{
	bool is_register = !!new;
	struct map_info *info;
	int err = 0;

	percpu_down_write(&dup_mmap_sem);
	info = build_map_info(uprobe->inode->i_mapping,
					uprobe->offset, is_register);
	if (IS_ERR(info)) {
		err = PTR_ERR(info);
		goto out;
	}

	while (info) {
		struct mm_struct *mm = info->mm;
		struct vm_area_struct *vma;

		if (err && is_register)
			goto free;

		down_write(&mm->mmap_sem);
		vma = find_vma(mm, info->vaddr);
		if (!vma || !valid_vma(vma, is_register) ||
		    file_inode(vma->vm_file) != uprobe->inode)
			goto unlock;

		if (vma->vm_start > info->vaddr ||
		    vaddr_to_offset(vma, info->vaddr) != uprobe->offset)
			goto unlock;

		if (is_register) {
			/* consult only the "caller", new consumer. */
			if (consumer_filter(new,
					UPROBE_FILTER_REGISTER, mm))
				err = install_breakpoint(uprobe, mm, vma, info->vaddr);
		} else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) {
			if (!filter_chain(uprobe,
					UPROBE_FILTER_UNREGISTER, mm))
				err |= remove_breakpoint(uprobe, mm, info->vaddr);
		}

 unlock:
		up_write(&mm->mmap_sem);
 free:
		mmput(mm);
		info = free_map_info(info);
	}
 out:
	percpu_up_write(&dup_mmap_sem);
	return err;
}

Project: linux
File: uprobes.c

static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
{
	struct vm_area_struct *vma;
	int ret;

	if (down_write_killable(&mm->mmap_sem))
		return -EINTR;

	if (mm->uprobes_state.xol_area) {
		ret = -EALREADY;
		goto fail;
	}

	if (!area->vaddr) {
		/* Try to map as high as possible, this is only a hint. */
		area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE,
						PAGE_SIZE, 0, 0);
		if (area->vaddr & ~PAGE_MASK) {
			ret = area->vaddr;
			goto fail;
		}
	}

	vma = _install_special_mapping(mm, area->vaddr, PAGE_SIZE,
				VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO,
				&area->xol_mapping);
	if (IS_ERR(vma)) {
		ret = PTR_ERR(vma);
		goto fail;
	}

	ret = 0;
	smp_wmb();	/* pairs with get_xol_area() */
	mm->uprobes_state.xol_area = area;
 fail:
	up_write(&mm->mmap_sem);

	return ret;
}

Project: linux
File: uprobes.c

static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp)
{
	struct mm_struct *mm = current->mm;
	struct uprobe *uprobe = NULL;
	struct vm_area_struct *vma;

	down_read(&mm->mmap_sem);
	vma = find_vma(mm, bp_vaddr);
	if (vma && vma->vm_start <= bp_vaddr) {
		if (valid_vma(vma, false)) {
			struct inode *inode = file_inode(vma->vm_file);
			loff_t offset = vaddr_to_offset(vma, bp_vaddr);

			uprobe = find_uprobe(inode, offset);
		}

		if (!uprobe)
			*is_swbp = is_trap_at_addr(mm, bp_vaddr);
	} else {
		*is_swbp = -EFAULT;
	}

	if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags))
		mmf_recalc_uprobes(mm);
	up_read(&mm->mmap_sem);

	return uprobe;
}

Project: linux
File: uprobes.c

static struct xol_area *__create_xol_area(unsigned long vaddr)
{
	struct mm_struct *mm = current->mm;
	uprobe_opcode_t insn = UPROBE_SWBP_INSN;
	struct xol_area *area;

	area = kmalloc(sizeof(*area), GFP_KERNEL);
	if (unlikely(!area))
		goto out;

	area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL);
	if (!area->bitmap)
		goto free_area;

	area->xol_mapping.name = "[uprobes]";
	area->xol_mapping.fault = NULL;
	area->xol_mapping.pages = area->pages;
	area->pages[0] = alloc_page(GFP_HIGHUSER);
	if (!area->pages[0])
		goto free_bitmap;
	area->pages[1] = NULL;

	area->vaddr = vaddr;
	init_waitqueue_head(&area->wq);
	/* Reserve the 1st slot for get_trampoline_vaddr() */
	set_bit(0, area->bitmap);
	atomic_set(&area->slot_count, 1);
	arch_uprobe_copy_ixol(area->pages[0], 0, &insn, UPROBE_SWBP_INSN_SIZE);

	if (!xol_add_vma(mm, area))
		return area;

	__free_page(area->pages[0]);
 free_bitmap:
	kfree(area->bitmap);
 free_area:
	kfree(area);
 out:
	return NULL;
}

Project: linux
File: uprobes.c

static void handle_trampoline(struct pt_regs *regs)
{
	struct uprobe_task *utask;
	struct return_instance *ri, *next;
	bool valid;

	utask = current->utask;
	if (!utask)
		goto sigill;

	ri = utask->return_instances;
	if (!ri)
		goto sigill;

	do {
		/*
		 * We should throw out the frames invalidated by longjmp().
		 * If this chain is valid, then the next one should be alive
		 * or NULL; the latter case means that nobody but ri->func
		 * could hit this trampoline on return. TODO: sigaltstack().
		 */
		next = find_next_ret_chain(ri);
		valid = !next || arch_uretprobe_is_alive(next, RP_CHECK_RET, regs);

		instruction_pointer_set(regs, ri->orig_ret_vaddr);
		do {
			if (valid)
				handle_uretprobe_chain(ri, regs);
			ri = free_ret_instance(ri);
			utask->depth--;
		} while (ri != next);
	} while (!valid);

	utask->return_instances = ri;
	return;

 sigill:
	uprobe_warn(current, "handle uretprobe, sending SIGILL.");
	force_sig_info(SIGILL, SEND_SIG_FORCED, current);

}

Project: linux
File: fork.c

struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
{
	struct mm_struct *mm;
	int err;

	err =  mutex_lock_killable(&task->signal->cred_guard_mutex);
	if (err)
		return ERR_PTR(err);

	mm = get_task_mm(task);
	if (mm && mm != current->mm &&
			!ptrace_may_access(task, mode)) {
		mmput(mm);
		mm = ERR_PTR(-EACCES);
	}
	mutex_unlock(&task->signal->cred_guard_mutex);

	return mm;
}

Project: linux
File: uprobes.c

void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm)
{
	if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) {
		set_bit(MMF_HAS_UPROBES, &newmm->flags);
		/* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */
		set_bit(MMF_RECALC_UPROBES, &newmm->flags);
	}
}

Project: linux
File: fork.c

static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
{
	struct files_struct *oldf, *newf;
	int error = 0;

	/*
	 * A background process may not have any files ...
	 */
	oldf = current->files;
	if (!oldf)
		goto out;

	if (clone_flags & CLONE_FILES) {
		atomic_inc(&oldf->count);
		goto out;
	}

	newf = dup_fd(oldf, &error);
	if (!newf)
		goto out;

	tsk->files = newf;
	error = 0;
out:
	return error;
}

Project: linux
File: uprobes.c

int uprobe_pre_sstep_notifier(struct pt_regs *regs)
{
	if (!current->mm)
		return 0;

	if (!test_bit(MMF_HAS_UPROBES, &current->mm->flags) &&
	    (!current->utask || !current->utask->return_instances))
		return 0;

	set_thread_flag(TIF_UPROBE);
	return 1;
}

Project: linux
File: uprobes.c

static void copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len)
{
	void *kaddr = kmap_atomic(page);
	memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len);
	kunmap_atomic(kaddr);
}

Project: linux
File: uprobes.c

static int __copy_insn(struct address_space *mapping, struct file *filp,
			void *insn, int nbytes, loff_t offset)
{
	struct page *page;
	/*
	 * Ensure that the page that has the original instruction is populated
	 * and in page-cache. If ->readpage == NULL it must be shmem_mapping(),
	 * see uprobe_register().
	 */
	if (mapping->a_ops->readpage)
		page = read_mapping_page(mapping, offset >> PAGE_SHIFT, filp);
	else
		page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT);
	if (IS_ERR(page))
		return PTR_ERR(page);

	copy_from_page(page, offset, insn, nbytes);
	put_page(page);

	return 0;
}

Project: linux
File: uprobes.c

static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs)
{
	struct uprobe *uprobe;
	int err = 0;

	uprobe = utask->active_uprobe;
	if (utask->state == UTASK_SSTEP_ACK)
		err = arch_uprobe_post_xol(&uprobe->arch, regs);
	else if (utask->state == UTASK_SSTEP_TRAPPED)
		arch_uprobe_abort_xol(&uprobe->arch, regs);
	else
		WARN_ON_ONCE(1);

	put_uprobe(uprobe);
	utask->active_uprobe = NULL;
	utask->state = UTASK_RUNNING;
	xol_free_insn_slot(current);

	spin_lock_irq(&current->sighand->siglock);
	recalc_sigpending(); /* see uprobe_deny_signal() */
	spin_unlock_irq(&current->sighand->siglock);

	if (unlikely(err)) {
		uprobe_warn(current, "execute the probed insn, sending SIGILL.");
		force_sig_info(SIGILL, SEND_SIG_FORCED, current);
	}
}

Project: linux
File: uprobes.c

bool uprobe_deny_signal(void)
{
	struct task_struct *t = current;
	struct uprobe_task *utask = t->utask;

	if (likely(!utask || !utask->active_uprobe))
		return false;

	WARN_ON_ONCE(utask->state != UTASK_SSTEP);

	if (signal_pending(t)) {
		spin_lock_irq(&t->sighand->siglock);
		clear_tsk_thread_flag(t, TIF_SIGPENDING);
		spin_unlock_irq(&t->sighand->siglock);

		if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) {
			utask->state = UTASK_SSTEP_TRAPPED;
			set_tsk_thread_flag(t, TIF_UPROBE);
		}
	}

	return true;
}

Project: linux
File: uprobes.c

void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
				  void *src, unsigned long len)
{
	/* Initialize the slot */
	copy_to_page(page, vaddr, src, len);

	/*
	 * We probably need flush_icache_user_range() but it needs vma.
	 * This should work on most of architectures by default. If
	 * architecture needs to do something different it can define
	 * its own version of the function.
	 */
	flush_dcache_page(page);
}

Project: linux
File: fork.c

static void posix_cpu_timers_init(struct task_struct *tsk)
{
	tsk->cputime_expires.prof_exp = 0;
	tsk->cputime_expires.virt_exp = 0;
	tsk->cputime_expires.sched_exp = 0;
	INIT_LIST_HEAD(&tsk->cpu_timers[0]);
	INIT_LIST_HEAD(&tsk->cpu_timers[1]);
	INIT_LIST_HEAD(&tsk->cpu_timers[2]);
}

Project: linux
File: uprobes.c

static bool filter_chain(struct uprobe *uprobe,
			 enum uprobe_filter_ctx ctx, struct mm_struct *mm)
{
	struct uprobe_consumer *uc;
	bool ret = false;

	down_read(&uprobe->consumer_rwsem);
	for (uc = uprobe->consumers; uc; uc = uc->next) {
		ret = consumer_filter(uc, ctx, mm);
		if (ret)
			break;
	}
	up_read(&uprobe->consumer_rwsem);

	return ret;
}

Project: linux
File: uprobes.c

void uprobe_end_dup_mmap(void)
{
	percpu_up_read(&dup_mmap_sem);
}

Project: linux
File: uprobes.c

pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr)
{
	struct uprobe_task *utask;
	unsigned long xol_vaddr;
	int err;

	utask = get_utask();
	if (!utask)
		return -ENOMEM;

	xol_vaddr = xol_get_insn_slot(uprobe);
	if (!xol_vaddr)
		return -ENOMEM;

	utask->xol_vaddr = xol_vaddr;
	utask->vaddr = bp_vaddr;

	err = arch_uprobe_pre_xol(&uprobe->arch, regs);
	if (unlikely(err)) {
		xol_free_insn_slot(current);
		return err;
	}

	utask->active_uprobe = uprobe;
	utask->state = UTASK_SSTEP;
	return 0;
}

Project: linux
File: uprobes.c

bool __weak is_swbp_insn(uprobe_opcode_t *insn)
{
	return *insn == UPROBE_SWBP_INSN;
}

Project: linux
File: uprobes.c

static struct xol_area *get_xol_area(void)
{
	struct mm_struct *mm = current->mm;
	struct xol_area *area;

	if (!mm->uprobes_state.xol_area)
		__create_xol_area(0);

	area = mm->uprobes_state.xol_area;
	smp_read_barrier_depends();	/* pairs with wmb in xol_add_vma() */
	return area;
}

Project: linux
File: uprobes.c

static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc)
{
	down_write(&uprobe->consumer_rwsem);
	uc->next = uprobe->consumers;
	uprobe->consumers = uc;
	up_write(&uprobe->consumer_rwsem);
}

Project: linux
File: uprobes.c

static inline bool consumer_filter(struct uprobe_consumer *uc,
				   enum uprobe_filter_ctx ctx, struct mm_struct *mm)
{
	return !uc->filter || uc->filter(uc, ctx, mm);
}

Project: linux
File: uprobes.c

int uprobe_post_sstep_notifier(struct pt_regs *regs)
{
	struct uprobe_task *utask = current->utask;

	if (!current->mm || !utask || !utask->active_uprobe)
		/* task is currently not uprobed */
		return 0;

	utask->state = UTASK_SSTEP_ACK;
	set_thread_flag(TIF_UPROBE);
	return 1;
}

Project: linux
File: uprobes.c

static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc)
{
	struct uprobe_consumer **con;
	bool ret = false;

	down_write(&uprobe->consumer_rwsem);
	for (con = &uprobe->consumers; *con; con = &(*con)->next) {
		if (*con == uc) {
			*con = uc->next;
			ret = true;
			break;
		}
	}
	up_write(&uprobe->consumer_rwsem);

	return ret;
}

Project: linux
File: uprobes.c

int uprobe_apply(struct inode *inode, loff_t offset,
			struct uprobe_consumer *uc, bool add)
{
	struct uprobe *uprobe;
	struct uprobe_consumer *con;
	int ret = -ENOENT;

	uprobe = find_uprobe(inode, offset);
	if (WARN_ON(!uprobe))
		return ret;

	down_write(&uprobe->register_rwsem);
	for (con = uprobe->consumers; con && con != uc ; con = con->next)
		;
	if (con)
		ret = register_for_each_vma(uprobe, add ? uc : NULL);
	up_write(&uprobe->register_rwsem);
	put_uprobe(uprobe);

	return ret;
}

Project: linux
File: uprobes.c

static unsigned long xol_take_insn_slot(struct xol_area *area)
{
	unsigned long slot_addr;
	int slot_nr;

	do {
		slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE);
		if (slot_nr < UINSNS_PER_PAGE) {
			if (!test_and_set_bit(slot_nr, area->bitmap))
				break;

			slot_nr = UINSNS_PER_PAGE;
			continue;
		}
		wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE));
	} while (slot_nr >= UINSNS_PER_PAGE);

	slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES);
	atomic_inc(&area->slot_count);

	return slot_addr;
}

Project: linux
File: uprobes.c

static int copy_insn(struct uprobe *uprobe, struct file *filp)
{
	struct address_space *mapping = uprobe->inode->i_mapping;
	loff_t offs = uprobe->offset;
	void *insn = &uprobe->arch.insn;
	int size = sizeof(uprobe->arch.insn);
	int len, err = -EIO;

	/* Copy only available bytes, -EIO if nothing was read */
	do {
		if (offs >= i_size_read(uprobe->inode))
			break;

		len = min_t(int, size, PAGE_SIZE - (offs & ~PAGE_MASK));
		err = __copy_insn(mapping, filp, insn, len, offs);
		if (err)
			break;

		insn += len;
		offs += len;
		size -= len;
	} while (size);

	return err;
}

Project: linux
File: uprobes.c

build_map_info(struct address_space *mapping, loff_t offset, bool is_register)
{
	unsigned long pgoff = offset >> PAGE_SHIFT;
	struct vm_area_struct *vma;
	struct map_info *curr = NULL;
	struct map_info *prev = NULL;
	struct map_info *info;
	int more = 0;

 again:
	i_mmap_lock_read(mapping);
	vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
		if (!valid_vma(vma, is_register))
			continue;

		if (!prev && !more) {
			/*
			 * Needs GFP_NOWAIT to avoid i_mmap_rwsem recursion through
			 * reclaim. This is optimistic, no harm done if it fails.
			 */
			prev = kmalloc(sizeof(struct map_info),
					GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN);
			if (prev)
				prev->next = NULL;
		}
		if (!prev) {
			more++;
			continue;
		}

		if (!mmget_not_zero(vma->vm_mm))
			continue;

		info = prev;
		prev = prev->next;
		info->next = curr;
		curr = info;

		info->mm = vma->vm_mm;
		info->vaddr = offset_to_vaddr(vma, offset);
	}
	i_mmap_unlock_read(mapping);

	if (!more)
		goto out;

	prev = curr;
	while (curr) {
		mmput(curr->mm);
		curr = curr->next;
	}

	do {
		info = kmalloc(sizeof(struct map_info), GFP_KERNEL);
		if (!info) {
			curr = ERR_PTR(-ENOMEM);
			goto out;
		}
		info->next = prev;
		prev = info;
	} while (--more);

	goto again;
 out:
	while (prev)
		prev = free_map_info(prev);
	return curr;
}

Project: linux
File: uprobes.c

bool __weak arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
					struct pt_regs *regs)
{
	return true;
}

Project: linux
File: uprobes.c

static void delete_uprobe(struct uprobe *uprobe)
{
	if (WARN_ON(!uprobe_is_active(uprobe)))
		return;

	spin_lock(&uprobes_treelock);
	rb_erase(&uprobe->rb_node, &uprobes_tree);
	spin_unlock(&uprobes_treelock);
	RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */
	iput(uprobe->inode);
	put_uprobe(uprobe);
}

Project: linux
File: uprobes.c

static unsigned long xol_get_insn_slot(struct uprobe *uprobe)
{
	struct xol_area *area;
	unsigned long xol_vaddr;

	area = get_xol_area();
	if (!area)
		return 0;

	xol_vaddr = xol_take_insn_slot(area);
	if (unlikely(!xol_vaddr))
		return 0;

	arch_uprobe_copy_ixol(area->pages[0], xol_vaddr,
			      &uprobe->arch.ixol, sizeof(uprobe->arch.ixol));

	return xol_vaddr;
}

Project: linux
File: uprobes.c

set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)
{
	return uprobe_write_opcode(mm, vaddr, *(uprobe_opcode_t *)&auprobe->insn);
}

Project: linux
File: uprobes.c

void uprobe_notify_resume(struct pt_regs *regs)
{
	struct uprobe_task *utask;

	clear_thread_flag(TIF_UPROBE);

	utask = current->utask;
	if (utask && utask->active_uprobe)
		handle_singlestep(utask, regs);
	else
		handle_swbp(regs);
}

Project: linux
File: uprobes.c

static int match_uprobe(struct uprobe *l, struct uprobe *r)
{
	if (l->inode < r->inode)
		return -1;

	if (l->inode > r->inode)
		return 1;

	if (l->offset < r->offset)
		return -1;

	if (l->offset > r->offset)
		return 1;

	return 0;
}

Project: linux
File: uprobes.c

static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm)
{
	struct vm_area_struct *vma;
	int err = 0;

	down_read(&mm->mmap_sem);
	for (vma = mm->mmap; vma; vma = vma->vm_next) {
		unsigned long vaddr;
		loff_t offset;

		if (!valid_vma(vma, false) ||
		    file_inode(vma->vm_file) != uprobe->inode)
			continue;

		offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
		if (uprobe->offset <  offset ||
		    uprobe->offset >= offset + vma->vm_end - vma->vm_start)
			continue;

		vaddr = offset_to_vaddr(vma, uprobe->offset);
		err |= remove_breakpoint(uprobe, mm, vaddr);
	}
	up_read(&mm->mmap_sem);

	return err;
}

Project: linux
File: uprobes.c

static struct uprobe *get_uprobe(struct uprobe *uprobe)
{
	atomic_inc(&uprobe->ref);
	return uprobe;
}

Project: linux
File: fork.c

static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
{
	struct sighand_struct *sig;

	if (clone_flags & CLONE_SIGHAND) {
		atomic_inc(&current->sighand->count);
		return 0;
	}
	sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
	rcu_assign_pointer(tsk->sighand, sig);
	if (!sig)
		return -ENOMEM;

	atomic_set(&sig->count, 1);
	memcpy(sig->action, current->sighand->action, sizeof(sig->action));
	return 0;
}

Project: linux
File: uprobes.c

static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset)
{
	return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
}

Project: linux
File: uprobes.c

static struct uprobe *find_uprobe(struct inode *inode, loff_t offset)
{
	struct uprobe *uprobe;

	spin_lock(&uprobes_treelock);
	uprobe = __find_uprobe(inode, offset);
	spin_unlock(&uprobes_treelock);

	return uprobe;
}

Project: linux
File: uprobes.c

void uprobe_copy_process(struct task_struct *t, unsigned long flags)
{
	struct uprobe_task *utask = current->utask;
	struct mm_struct *mm = current->mm;
	struct xol_area *area;

	t->utask = NULL;

	if (!utask || !utask->return_instances)
		return;

	if (mm == t->mm && !(flags & CLONE_VFORK))
		return;

	if (dup_utask(t, utask))
		return uprobe_warn(t, "dup ret instances");

	/* The task can fork() after dup_xol_work() fails */
	area = mm->uprobes_state.xol_area;
	if (!area)
		return uprobe_warn(t, "dup xol area");

	if (mm == t->mm)
		return;

	t->utask->dup_xol_addr = area->vaddr;
	init_task_work(&t->utask->dup_xol_work, dup_xol_work);
	task_work_add(t, &t->utask->dup_xol_work, true);
}

Project: linux
File: uprobes.c

static void xol_free_insn_slot(struct task_struct *tsk)
{
	struct xol_area *area;
	unsigned long vma_end;
	unsigned long slot_addr;

	if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask)
		return;

	slot_addr = tsk->utask->xol_vaddr;
	if (unlikely(!slot_addr))
		return;

	area = tsk->mm->uprobes_state.xol_area;
	vma_end = area->vaddr + PAGE_SIZE;
	if (area->vaddr <= slot_addr && slot_addr < vma_end) {
		unsigned long offset;
		int slot_nr;

		offset = slot_addr - area->vaddr;
		slot_nr = offset / UPROBE_XOL_SLOT_BYTES;
		if (slot_nr >= UINSNS_PER_PAGE)
			return;

		clear_bit(slot_nr, area->bitmap);
		atomic_dec(&area->slot_count);
		smp_mb__after_atomic(); /* pairs with prepare_to_wait() */
		if (waitqueue_active(&area->wq))
			wake_up(&area->wq);

		tsk->utask->xol_vaddr = 0;
	}
}

Project: linux
File: uprobes.c

bool __weak is_trap_insn(uprobe_opcode_t *insn)
{
	return is_swbp_insn(insn);
}

Project: linux
File: uprobes.c

install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
			struct vm_area_struct *vma, unsigned long vaddr)
{
	bool first_uprobe;
	int ret;

	ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr);
	if (ret)
		return ret;

	/*
	 * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(),
	 * the task can hit this breakpoint right after __replace_page().
	 */
	first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags);
	if (first_uprobe)
		set_bit(MMF_HAS_UPROBES, &mm->flags);

	ret = set_swbp(&uprobe->arch, mm, vaddr);
	if (!ret)
		clear_bit(MMF_RECALC_UPROBES, &mm->flags);
	else if (first_uprobe)
		clear_bit(MMF_HAS_UPROBES, &mm->flags);

	return ret;
}

Project: linux
File: uprobes.c

void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
{
	struct uprobe *uprobe;

	uprobe = find_uprobe(inode, offset);
	if (WARN_ON(!uprobe))
		return;

	down_write(&uprobe->register_rwsem);
	__uprobe_unregister(uprobe, uc);
	up_write(&uprobe->register_rwsem);
	put_uprobe(uprobe);
}

Project: linux
File: uprobes.c

static int __init init_uprobes(void)
{
	int i;

	for (i = 0; i < UPROBES_HASH_SZ; i++)
		mutex_init(&uprobes_mmap_mutex[i]);

	if (percpu_init_rwsem(&dup_mmap_sem))
		return -ENOMEM;

	return register_die_notifier(&uprobe_exception_nb);
}

Project: linux
File: uprobes.c

void uprobe_start_dup_mmap(void)
{
	percpu_down_read(&dup_mmap_sem);
}

Project: linux
File: uprobes.c

vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end)
{
	loff_t min, max;
	struct inode *inode;
	struct rb_node *n;

	inode = file_inode(vma->vm_file);

	min = vaddr_to_offset(vma, start);
	max = min + (end - start) - 1;

	spin_lock(&uprobes_treelock);
	n = find_node_in_range(inode, min, max);
	spin_unlock(&uprobes_treelock);

	return !!n;
}

Project: linux
File: uprobes.c

static inline struct map_info *free_map_info(struct map_info *info)
{
	struct map_info *next = info->next;
	kfree(info);
	return next;
}

Project: linux
File: uprobes.c

static inline bool uprobe_is_active(struct uprobe *uprobe)
{
	return !RB_EMPTY_NODE(&uprobe->rb_node);
}

Project: linux
File: uprobes.c

static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr)
{
	return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start);
}

Project: linux
File: uprobes.c

static void build_probe_list(struct inode *inode,
				struct vm_area_struct *vma,
				unsigned long start, unsigned long end,
				struct list_head *head)
{
	loff_t min, max;
	struct rb_node *n, *t;
	struct uprobe *u;

	INIT_LIST_HEAD(head);
	min = vaddr_to_offset(vma, start);
	max = min + (end - start) - 1;

	spin_lock(&uprobes_treelock);
	n = find_node_in_range(inode, min, max);
	if (n) {
		for (t = n; t; t = rb_prev(t)) {
			u = rb_entry(t, struct uprobe, rb_node);
			if (u->inode != inode || u->offset < min)
				break;
			list_add(&u->pending_list, head);
			get_uprobe(u);
		}
		for (t = n; (t = rb_next(t)); ) {
			u = rb_entry(t, struct uprobe, rb_node);
			if (u->inode != inode || u->offset > max)
				break;
			list_add(&u->pending_list, head);
			get_uprobe(u);
		}
	}
	spin_unlock(&uprobes_treelock);
}

Project: linux
File: uprobes.c

static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
{
	struct return_instance *ri;
	struct uprobe_task *utask;
	unsigned long orig_ret_vaddr, trampoline_vaddr;
	bool chained;

	if (!get_xol_area())
		return;

	utask = get_utask();
	if (!utask)
		return;

	if (utask->depth >= MAX_URETPROBE_DEPTH) {
		printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to"
				" nestedness limit pid/tgid=%d/%d\n",
				current->pid, current->tgid);
		return;
	}

	ri = kmalloc(sizeof(struct return_instance), GFP_KERNEL);
	if (!ri)
		return;

	trampoline_vaddr = get_trampoline_vaddr();
	orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs);
	if (orig_ret_vaddr == -1)
		goto fail;

	/* drop the entries invalidated by longjmp() */
	chained = (orig_ret_vaddr == trampoline_vaddr);
	cleanup_return_instances(utask, chained, regs);

	/*
	 * We don't want to keep trampoline address in stack, rather keep the
	 * original return address of first caller thru all the consequent
	 * instances. This also makes breakpoint unwrapping easier.
	 */
	if (chained) {
		if (!utask->return_instances) {
			/*
			 * This situation is not possible. Likely we have an
			 * attack from user-space.
			 */
			uprobe_warn(current, "handle tail call");
			goto fail;
		}
		orig_ret_vaddr = utask->return_instances->orig_ret_vaddr;
	}

	ri->uprobe = get_uprobe(uprobe);
	ri->func = instruction_pointer(regs);
	ri->stack = user_stack_pointer(regs);
	ri->orig_ret_vaddr = orig_ret_vaddr;
	ri->chained = chained;

	utask->depth++;
	ri->next = utask->return_instances;
	utask->return_instances = ri;

	return;
 fail:
	kfree(ri);
}

Project: linux
File: uprobes.c

static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs)
{
	struct uprobe_consumer *uc;
	int remove = UPROBE_HANDLER_REMOVE;
	bool need_prep = false; /* prepare return uprobe, when needed */

	down_read(&uprobe->register_rwsem);
	for (uc = uprobe->consumers; uc; uc = uc->next) {
		int rc = 0;

		if (uc->handler) {
			rc = uc->handler(uc, regs);
			WARN(rc & ~UPROBE_HANDLER_MASK,
				"bad rc=0x%x from %pf()\n", rc, uc->handler);
		}

		if (uc->ret_handler)
			need_prep = true;

		remove &= rc;
	}

	if (need_prep && !remove)
		prepare_uretprobe(uprobe, regs); /* put bp at return */

	if (remove && uprobe->consumers) {
		WARN_ON(!uprobe_is_active(uprobe));
		unapply_uprobe(uprobe, current->mm);
	}
	up_read(&uprobe->register_rwsem);
}

Project: linux
File: uprobes.c

static struct uprobe_task *get_utask(void)
{
	if (!current->utask)
		current->utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL);
	return current->utask;
}

Project: linux
File: uprobes.c

static void cleanup_return_instances(struct uprobe_task *utask, bool chained,
					struct pt_regs *regs)
{
	struct return_instance *ri = utask->return_instances;
	enum rp_check ctx = chained ? RP_CHECK_CHAIN_CALL : RP_CHECK_CALL;

	while (ri && !arch_uretprobe_is_alive(ri, ctx, regs)) {
		ri = free_ret_instance(ri);
		utask->depth--;
	}
	utask->return_instances = ri;
}

Project: linux
File: uprobes.c

static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
				struct page *old_page, struct page *new_page)
{
	struct mm_struct *mm = vma->vm_mm;
	struct page_vma_mapped_walk pvmw = {
		.page = old_page,
		.vma = vma,
		.address = addr,
	};
	int err;
	/* For mmu_notifiers */
	const unsigned long mmun_start = addr;
	const unsigned long mmun_end   = addr + PAGE_SIZE;
	struct mem_cgroup *memcg;

	VM_BUG_ON_PAGE(PageTransHuge(old_page), old_page);

	err = mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL, &memcg,
			false);
	if (err)
		return err;

	/* For try_to_free_swap() and munlock_vma_page() below */
	lock_page(old_page);

	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
	err = -EAGAIN;
	if (!page_vma_mapped_walk(&pvmw)) {
		mem_cgroup_cancel_charge(new_page, memcg, false);
		goto unlock;
	}
	VM_BUG_ON_PAGE(addr != pvmw.address, old_page);

	get_page(new_page);
	page_add_new_anon_rmap(new_page, vma, addr, false);
	mem_cgroup_commit_charge(new_page, memcg, false, false);
	lru_cache_add_active_or_unevictable(new_page, vma);

	if (!PageAnon(old_page)) {
		dec_mm_counter(mm, mm_counter_file(old_page));
		inc_mm_counter(mm, MM_ANONPAGES);
	}

	flush_cache_page(vma, addr, pte_pfn(*pvmw.pte));
	ptep_clear_flush_notify(vma, addr, pvmw.pte);
	set_pte_at_notify(mm, addr, pvmw.pte,
			mk_pte(new_page, vma->vm_page_prot));

	page_remove_rmap(old_page, false);
	if (!page_mapped(old_page))
		try_to_free_swap(old_page);
	page_vma_mapped_walk_done(&pvmw);

	if (vma->vm_flags & VM_LOCKED)
		munlock_vma_page(old_page);
	put_page(old_page);

	err = 0;
 unlock:
	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
	unlock_page(old_page);
	return err;
}

Project: linux
File: fork.c

static inline void init_idle_pids(struct pid_link *links)
{
	enum pid_type type;

	for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
		INIT_HLIST_NODE(&links[type].node); /* not really needed */
		links[type].pid = &init_struct_pid;
	}
}

Project: linux
File: uprobes.c

static int prepare_uprobe(struct uprobe *uprobe, struct file *file,
				struct mm_struct *mm, unsigned long vaddr)
{
	int ret = 0;

	if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))
		return ret;

	/* TODO: move this into _register, until then we abuse this sem. */
	down_write(&uprobe->consumer_rwsem);
	if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))
		goto out;

	ret = copy_insn(uprobe, file);
	if (ret)
		goto out;

	ret = -ENOTSUPP;
	if (is_trap_insn((uprobe_opcode_t *)&uprobe->arch.insn))
		goto out;

	ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr);
	if (ret)
		goto out;

	/* uprobe_write_opcode() assumes we don't cross page boundary */
	BUG_ON((uprobe->offset & ~PAGE_MASK) +
			UPROBE_SWBP_INSN_SIZE > PAGE_SIZE);

	smp_wmb(); /* pairs with rmb() in find_active_uprobe() */
	set_bit(UPROBE_COPY_INSN, &uprobe->flags);

 out:
	up_write(&uprobe->consumer_rwsem);

	return ret;
}

Project: linux
File: uprobes.c

static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr)
{
	struct page *page;
	uprobe_opcode_t opcode;
	int result;

	pagefault_disable();
	result = __get_user(opcode, (uprobe_opcode_t __user *)vaddr);
	pagefault_enable();

	if (likely(result == 0))
		goto out;

	/*
	 * The NULL 'tsk' here ensures that any faults that occur here
	 * will not be accounted to the task.  'mm' *is* current->mm,
	 * but we treat this as a 'remote' access since it is
	 * essentially a kernel access to the memory.
	 */
	result = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &page,
			NULL, NULL);
	if (result < 0)
		return result;

	copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
	put_page(page);
 out:
	/* This needs to return true for any variant of the trap insn */
	return is_trap_insn(&opcode);
}

Project: linux
File: uprobes.c

static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset)
{
	struct uprobe u = { .inode = inode, .offset = offset };
	struct rb_node *n = uprobes_tree.rb_node;
	struct uprobe *uprobe;
	int match;

	while (n) {
		uprobe = rb_entry(n, struct uprobe, rb_node);
		match = match_uprobe(&u, uprobe);
		if (!match)
			return get_uprobe(uprobe);

		if (match < 0)
			n = n->rb_left;
		else
			n = n->rb_right;
	}
	return NULL;
}

Project: linux
File: uprobes.c

bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs)
{
	return false;
}

Project: linux
File: uprobes.c

static void dup_xol_work(struct callback_head *work)
{
	if (current->flags & PF_EXITING)
		return;

	if (!__create_xol_area(current->utask->dup_xol_addr) &&
			!fatal_signal_pending(current))
		uprobe_warn(current, "dup xol area");
}

Project: linux
File: uprobes.c

static void put_uprobe(struct uprobe *uprobe)
{
	if (atomic_dec_and_test(&uprobe->ref))
		kfree(uprobe);
}

Project: linux
File: uprobes.c

static void handle_swbp(struct pt_regs *regs)
{
	struct uprobe *uprobe;
	unsigned long bp_vaddr;
	int uninitialized_var(is_swbp);

	bp_vaddr = uprobe_get_swbp_addr(regs);
	if (bp_vaddr == get_trampoline_vaddr())
		return handle_trampoline(regs);

	uprobe = find_active_uprobe(bp_vaddr, &is_swbp);
	if (!uprobe) {
		if (is_swbp > 0) {
			/* No matching uprobe; signal SIGTRAP. */
			send_sig(SIGTRAP, current, 0);
		} else {
			/*
			 * Either we raced with uprobe_unregister() or we can't
			 * access this memory. The latter is only possible if
			 * another thread plays with our ->mm. In both cases
			 * we can simply restart. If this vma was unmapped we
			 * can pretend this insn was not executed yet and get
			 * the (correct) SIGSEGV after restart.
			 */
			instruction_pointer_set(regs, bp_vaddr);
		}
		return;
	}

	/* change it in advance for ->handler() and restart */
	instruction_pointer_set(regs, bp_vaddr);

	/*
	 * TODO: move copy_insn/etc into _register and remove this hack.
	 * After we hit the bp, _unregister + _register can install the
	 * new and not-yet-analyzed uprobe at the same address, restart.
	 */
	smp_rmb(); /* pairs with wmb() in install_breakpoint() */
	if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags)))
		goto out;

	/* Tracing handlers use ->utask to communicate with fetch methods */
	if (!get_utask())
		goto out;

	if (arch_uprobe_ignore(&uprobe->arch, regs))
		goto out;

	handler_chain(uprobe, regs);

	if (arch_uprobe_skip_sstep(&uprobe->arch, regs))
		goto out;

	if (!pre_ssout(uprobe, regs, bp_vaddr))
		return;

	/* arch_uprobe_skip_sstep() succeeded, or restart if can't singlestep */
out:
	put_uprobe(uprobe);
}

Project: linux
File: uprobes.c

static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len)
{
	void *kaddr = kmap_atomic(page);
	memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len);
	kunmap_atomic(kaddr);
}

Project: linux
File: uprobes.c

static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc)
{
	consumer_add(uprobe, uc);
	return register_for_each_vma(uprobe, uc);
}

Project: linux
File: uprobes.c

void uprobe_free_utask(struct task_struct *t)
{
	struct uprobe_task *utask = t->utask;
	struct return_instance *ri;

	if (!utask)
		return;

	if (utask->active_uprobe)
		put_uprobe(utask->active_uprobe);

	ri = utask->return_instances;
	while (ri)
		ri = free_ret_instance(ri);

	xol_free_insn_slot(t);
	kfree(utask);
	t->utask = NULL;
}

Project: linux
File: uprobes.c

void uprobe_clear_state(struct mm_struct *mm)
{
	struct xol_area *area = mm->uprobes_state.xol_area;

	if (!area)
		return;

	put_page(area->pages[0]);
	kfree(area->bitmap);
	kfree(area);
}

Project: linux
File: uprobes.c

static struct return_instance *find_next_ret_chain(struct return_instance *ri)
{
	bool chained;

	do {
		chained = ri->chained;
		ri = ri->next;	/* can't be NULL if chained */
	} while (chained);

	return ri;
}

Project: linux
File: fork.c

static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
{
	struct files_struct *fd = current->files;
	int error = 0;

	if ((unshare_flags & CLONE_FILES) &&
	    (fd && atomic_read(&fd->count) > 1)) {
		*new_fdp = dup_fd(fd, &error);
		if (!*new_fdp)
			return error;
	}

	return 0;
}

Project: linux
File: fork.c

SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
		 int __user *, parent_tidptr,
		 int __user *, child_tidptr,
		 unsigned long, tls)
#endif
{
	return _do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr, tls);
}

Project: linux
File: uprobes.c

static void uprobe_warn(struct task_struct *t, const char *msg)
{
	pr_warn("uprobe: %s:%d failed to %s\n",
			current->comm, current->pid, msg);
}

Project: linux
File: fork.c

static inline void put_signal_struct(struct signal_struct *sig)
{
	if (atomic_dec_and_test(&sig->sigcnt))
		free_signal_struct(sig);
}

Project: linux
File: fork.c

static int wait_for_vfork_done(struct task_struct *child,
				struct completion *vfork)
{
	int killed;

	freezer_do_not_count();
	killed = wait_for_completion_killable(vfork);
	freezer_count();

	if (killed) {
		task_lock(child);
		child->vfork_done = NULL;
		task_unlock(child);
	}

	put_task_struct(child);
	return killed;
}

Project: linux
File: uprobes.c

static unsigned long get_trampoline_vaddr(void)
{
	struct xol_area *area;
	unsigned long trampoline_vaddr = -1;

	area = current->mm->uprobes_state.xol_area;
	smp_read_barrier_depends();
	if (area)
		trampoline_vaddr = area->vaddr;

	return trampoline_vaddr;
}

Project: linux
File: uprobes.c

int uprobe_mmap(struct vm_area_struct *vma)
{
	struct list_head tmp_list;
	struct uprobe *uprobe, *u;
	struct inode *inode;

	if (no_uprobe_events() || !valid_vma(vma, true))
		return 0;

	inode = file_inode(vma->vm_file);
	if (!inode)
		return 0;

	mutex_lock(uprobes_mmap_hash(inode));
	build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list);
	/*
	 * We can race with uprobe_unregister(), this uprobe can be already
	 * removed. But in this case filter_chain() must return false, all
	 * consumers have gone away.
	 */
	list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
		if (!fatal_signal_pending(current) &&
		    filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) {
			unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset);
			install_breakpoint(uprobe, vma->vm_mm, vma, vaddr);
		}
		put_uprobe(uprobe);
	}
	mutex_unlock(uprobes_mmap_hash(inode));

	return 0;
}

Project: linux
File: uprobes.c

static struct return_instance *free_ret_instance(struct return_instance *ri)
{
	struct return_instance *next = ri->next;
	put_uprobe(ri->uprobe);
	kfree(ri);
	return next;
}

Project: linux
File: uprobes.c

unsigned long uprobe_get_trap_addr(struct pt_regs *regs)
{
	struct uprobe_task *utask = current->utask;

	if (unlikely(utask && utask->active_uprobe))
		return utask->vaddr;

	return instruction_pointer(regs);
}

Project: linux
File: uprobes.c

static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset)
{
	struct uprobe *uprobe, *cur_uprobe;

	uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL);
	if (!uprobe)
		return NULL;

	uprobe->inode = igrab(inode);
	uprobe->offset = offset;
	init_rwsem(&uprobe->register_rwsem);
	init_rwsem(&uprobe->consumer_rwsem);

	/* add to uprobes_tree, sorted on inode:offset */
	cur_uprobe = insert_uprobe(uprobe);
	/* a uprobe exists for this inode:offset combination */
	if (cur_uprobe) {
		kfree(uprobe);
		uprobe = cur_uprobe;
		iput(inode);
	}

	return uprobe;
}