futex: Prevent attaching to kernel threads

We happily allow userspace to declare a random kernel thread to be the
owner of a user space PI futex.

Found while analysing the fallout of Dave Jones syscall fuzzer.

We also should validate the thread group for private futexes and find
some fast way to validate whether the "alleged" owner has RW access on
the file which backs the SHM, but that's a separate issue.

Change-Id: I03941dc5737bcb9d3ddd2ec88f7c263c27a1247d
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Jones <davej@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Darren Hart <darren@dvhart.com>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Clark Williams <williams@redhat.com>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Carlos ODonell <carlos@redhat.com>
Cc: Jakub Jelinek <jakub@redhat.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: http://lkml.kernel.org/r/20140512201701.194824402@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
futex: Add another early deadlock detection check

Dave Jones trinity syscall fuzzer exposed an issue in the deadlock
detection code of rtmutex:
  http://lkml.kernel.org/r/20140429151655.GA14277@redhat.com

That underlying issue has been fixed with a patch to the rtmutex code,
but the futex code must not call into rtmutex in that case because
    - it can detect that issue early
    - it avoids a different and more complex fixup for backing out

If the user space variable got manipulated to 0x80000000 which means
no lock holder, but the waiters bit set and an active pi_state in the
kernel is found we can figure out the recursive locking issue by
looking at the pi_state owner. If that is the current task, then we
can safely return -EDEADLK.

The check should have been added in commit 59fa62451 (futex: Handle
futex_pi OWNER_DIED take over correctly) already, but I did not see
the above issue caused by user space manipulation back then.

Change-Id: I5242efcdc3c08159c652fe645e1f85b27687e6ca
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Jones <davej@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Darren Hart <darren@dvhart.com>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Clark Williams <williams@redhat.com>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Carlos ODonell <carlos@redhat.com>
Cc: Jakub Jelinek <jakub@redhat.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: http://lkml.kernel.org/r/20140512201701.097349971@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
futex-prevent-requeue-pi-on-same-futex.patch futex: Forbid uaddr == uaddr2 in futex_requeue(..., requeue_pi=1)

If uaddr == uaddr2, then we have broken the rule of only requeueing
from a non-pi futex to a pi futex with this call. If we attempt this,
then dangling pointers may be left for rt_waiter resulting in an
exploitable condition.

This change brings futex_requeue() into line with
futex_wait_requeue_pi() which performs the same check as per commit
6f7b0a2a5 (futex: Forbid uaddr == uaddr2 in futex_wait_requeue_pi())

[ tglx: Compare the resulting keys as well, as uaddrs might be
  	different depending on the mapping ]

Fixes CVE-2014-3153.

Change-Id: I473bf486ad451de0bfd049a110b69795a6fda451
Reported-by: Pinkie Pie
Signed-off-by: Will Drewry <wad@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
futex: Validate atomic acquisition in futex_lock_pi_atomic()

We need to protect the atomic acquisition in the kernel against rogue
user space which sets the user space futex to 0, so the kernel side
acquisition succeeds while there is existing state in the kernel
associated to the real owner.

Verify whether the futex has waiters associated with kernel state. If
it has, return -EINVAL. The state is corrupted already, so no point in
cleaning it up. Subsequent calls will fail as well. Not our problem.

[ tglx: Use futex_top_waiter() and explain why we do not need to try
  	restoring the already corrupted user space state. ]

Change-Id: Ic8714ed2e9dee323a011eed42f7c0159c65dfbf3
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Drewry <wad@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
futex: Always cleanup owner tid in unlock_pi

If the owner died bit is set at futex_unlock_pi, we currently do not
cleanup the user space futex. So the owner TID of the current owner
(the unlocker) persists. That's observable inconsistant state,
especially when the ownership of the pi state got transferred.

Clean it up unconditionally.

Change-Id: I4eeb2e139b720f1dd46e43407a96b3d9a19aacd1
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Drewry <wad@chromium.org>
Cc: Darren Hart <dvhart@linux.intel.com>
Cc: stable@vger.kernel.org
futex: Make lookup_pi_state more robust

The current implementation of lookup_pi_state has ambigous handling of
the TID value 0 in the user space futex. We can get into the kernel
even if the TID value is 0, because either there is a stale waiters
bit or the owner died bit is set or we are called from the requeue_pi
path or from user space just for fun.

The current code avoids an explicit sanity check for pid = 0 in case
that kernel internal state (waiters) are found for the user space
address. This can lead to state leakage and worse under some
circumstances.

Handle the cases explicit:

     Waiter | pi_state | pi->owner | uTID      | uODIED | ?

[1]  NULL   | ---      | ---       | 0         | 0/1    | Valid
[2]  NULL   | ---      | ---       | >0        | 0/1    | Valid

[3]  Found  | NULL     | --        | Any       | 0/1    | Invalid

[4]  Found  | Found    | NULL      | 0         | 1      | Valid
[5]  Found  | Found    | NULL      | >0        | 1      | Invalid

[6]  Found  | Found    | task      | 0         | 1      | Valid

[7]  Found  | Found    | NULL      | Any       | 0      | Invalid

[8]  Found  | Found    | task      | ==taskTID | 0/1    | Valid
[9]  Found  | Found    | task      | 0         | 0      | Invalid
[10] Found  | Found    | task      | !=taskTID | 0/1    | Invalid

[1]  Indicates that the kernel can acquire the futex atomically. We
     came came here due to a stale FUTEX_WAITERS/FUTEX_OWNER_DIED bit.

[2]  Valid, if TID does not belong to a kernel thread. If no matching
     thread is found then it indicates that the owner TID has died.

[3]  Invalid. The waiter is queued on a non PI futex

[4]  Valid state after exit_robust_list(), which sets the user space
     value to FUTEX_WAITERS | FUTEX_OWNER_DIED.

[5]  The user space value got manipulated between exit_robust_list()
     and exit_pi_state_list()

[6]  Valid state after exit_pi_state_list() which sets the new owner in
     the pi_state but cannot access the user space value.

[7]  pi_state->owner can only be NULL when the OWNER_DIED bit is set.

[8]  Owner and user space value match

[9]  There is no transient state which sets the user space TID to 0
     except exit_robust_list(), but this is indicated by the
     FUTEX_OWNER_DIED bit. See [4]

[10] There is no transient state which leaves owner and user space
     TID out of sync.

Backport to 3.13
  conflicts: kernel/futex.c

Change-Id: Ic410036b38ccb7289b3d58eff56ad64d3a9dcada
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Drewry <wad@chromium.org>
Cc: Darren Hart <dvhart@linux.intel.com>
Cc: stable@vger.kernel.org
set min battery level to 1
board-omap4panda.c: omap_vwlan_device define but not used
epoll: optimize EPOLL_CTL_DEL using rcu
lib: make _tolower() public
ext4: remove the resize mount option
The resize mount option seems to be of limited value, especially in the age of online resize2fs. Nuke it. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
ext4: remove the journal=update mount option
The V2 journal format was introduced around ten years ago, for ext3. It seems highly unlikely that anyone will need this migration option for ext4. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
setup SmartReflex
ARM: Add init_consistent_dma_size()

This function can be called during boot to increase the size of the consistent
DMA region above it's default value of 2MB. It must be called before the memory
allocator is initialised, i.e. before any core_initcall.

Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>

Conflicts:
	arch/arm/include/asm/dma-mapping.h
ARM: Remove support for macro CONSISTENT_DMA_SIZE

There are now no platforms which set this macro.

Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
arm: Increase the DMA consistent memory zone to 4MB

Increase the zone for mapping DMA memory on most platforms from 2MB
to 4 MB. The actual memory comes from the normal pool, this
change just increases the virtual range where the memory can be mappped
(at the cost of 1 more 2MB pagetable).
introduce for_each_thread() to replace the buggy while_each_thread()

while_each_thread() and next_thread() should die, almost every lockless
usage is wrong.

1. Unless g == current, the lockless while_each_thread() is not safe.

   while_each_thread(g, t) can loop forever if g exits, next_thread()
   can't reach the unhashed thread in this case. Note that this can
   happen even if g is the group leader, it can exec.

2. Even if while_each_thread() itself was correct, people often use
   it wrongly.

   It was never safe to just take rcu_read_lock() and loop unless
   you verify that pid_alive(g) == T, even the first next_thread()
   can point to the already freed/reused memory.

This patch adds signal_struct->thread_head and task->thread_node to
create the normal rcu-safe list with the stable head.  The new
for_each_thread(g, t) helper is always safe under rcu_read_lock() as
long as this task_struct can't go away.

Note: of course it is ugly to have both task_struct->thread_node and the
old task_struct->thread_group, we will kill it later, after we change
the users of while_each_thread() to use for_each_thread().

Perhaps we can kill it even before we convert all users, we can
reimplement next_thread(t) using the new thread_head/thread_node.  But
we can't do this right now because this will lead to subtle behavioural
changes.  For example, do/while_each_thread() always sees at least one
task, while for_each_thread() can do nothing if the whole thread group
has died.  Or thread_group_empty(), currently its semantics is not clear
unless thread_group_leader(p) and we need to audit the callers before we
can change it.

So this patch adds the new interface which has to coexist with the old
one for some time, hopefully the next changes will be more or less
straightforward and the old one will go away soon.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Sergey Dyasly <dserrg@gmail.com>
Tested-by: Sergey Dyasly <dserrg@gmail.com>
Reviewed-by: Sameer Nanda <snanda@chromium.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mandeep Singh Baines <msb@chromium.org>
Cc: "Ma, Xindong" <xindong.ma@intel.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: "Tu, Xiaobing" <xiaobing.tu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul Reioux <reioux@gmail.com>

backported to Linux 3.4

Conflicts:
	kernel/fork.c

Conflicts:
	include/linux/init_task.h

Conflicts:
	arch/arm/boot/zImage
introduce for_each_thread() to replace the buggy while_each_thread() (fix)

fix a merge derp. pointed out by neobuddy89

Signed-off-by: Paul Reioux <reioux@gmail.com>
OMAP4: DVFS: Fix scaling dependent frequencies.

When scaling dependent frequencies down it is observed that the order
in which frequencies are changed is incorrect.  For example, when core
domain changes OPP down from OPP119 to OPP50 the order is:
a) scale L3 freq down to OPP50
b) scale SGX freq down to OPP50
which is wrong.

Frequencies are scaled in order devices are registered in omap dvfs
framework in device list. Devices are inserted to the list in order,
such as dependences are satisfied if scaling frequencies up.

When scaling frequencies down traverse list backwards.

Change-Id: I752bcb264cac12514f358986a906f29ee81ba75e
Signed-off-by: Oleksandr Kozaruk <oleksandr.kozaruk@ti.com>
mm: Do not stall in synchronous compaction for THP allocations