x86/mm: Check if PUD is large when validating a kernel address

commit 0ee364eb316348ddf3e0dfcd986f5f13f528f821 upstream.

A user reported the following oops when a backup process reads
/proc/kcore:

 BUG: unable to handle kernel paging request at ffffbb00ff33b000
 IP: [<ffffffff8103157e>] kern_addr_valid+0xbe/0x110
 [...]

 Call Trace:
  [<ffffffff811b8aaa>] read_kcore+0x17a/0x370
  [<ffffffff811ad847>] proc_reg_read+0x77/0xc0
  [<ffffffff81151687>] vfs_read+0xc7/0x130
  [<ffffffff811517f3>] sys_read+0x53/0xa0
  [<ffffffff81449692>] system_call_fastpath+0x16/0x1b

Investigation determined that the bug triggered when reading
system RAM at the 4G mark. On this system, that was the first
address using 1G pages for the virt->phys direct mapping so the
PUD is pointing to a physical address, not a PMD page.

The problem is that the page table walker in kern_addr_valid() is
not checking pud_large() and treats the physical address as if
it was a PMD.  If it happens to look like pmd_none then it'll
silently fail, probably returning zeros instead of real data. If
the data happens to look like a present PMD though, it will be
walked resulting in the oops above.

This patch adds the necessary pud_large() check.

Unfortunately the problem was not readily reproducible and now
they are running the backup program without accessing
/proc/kcore so the patch has not been validated but I think it
makes sense.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.coM>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20130211145236.GX21389@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
x86/xen: don't assume %ds is usable in xen_iret for 32-bit PVOPS.

commit 13d2b4d11d69a92574a55bfd985cfb0ca77aebdc upstream.

This fixes CVE-2013-0228 / XSA-42

Drew Jones while working on CVE-2013-0190 found that that unprivileged guest user
in 32bit PV guest can use to crash the > guest with the panic like this:

-------------
general protection fault: 0000 [#1] SMP
last sysfs file: /sys/devices/vbd-51712/block/xvda/dev
Modules linked in: sunrpc ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4
iptable_filter ip_tables ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6
xt_state nf_conntrack ip6table_filter ip6_tables ipv6 xen_netfront ext4
mbcache jbd2 xen_blkfront dm_mirror dm_region_hash dm_log dm_mod [last
unloaded: scsi_wait_scan]

Pid: 1250, comm: r Not tainted 2.6.32-356.el6.i686 #1
EIP: 0061:[<c0407462>] EFLAGS: 00010086 CPU: 0
EIP is at xen_iret+0x12/0x2b
EAX: eb8d0000 EBX: 00000001 ECX: 08049860 EDX: 00000010
ESI: 00000000 EDI: 003d0f00 EBP: b77f8388 ESP: eb8d1fe0
 DS: 0000 ES: 007b FS: 0000 GS: 00e0 SS: 0069
Process r (pid: 1250, ti=eb8d0000 task=c2953550 task.ti=eb8d0000)
Stack:
 00000000 0027f416 00000073 00000206 b77f8364 0000007b 00000000 00000000
Call Trace:
Code: c3 8b 44 24 18 81 4c 24 38 00 02 00 00 8d 64 24 30 e9 03 00 00 00
8d 76 00 f7 44 24 08 00 00 02 80 75 33 50 b8 00 e0 ff ff 21 e0 <8b> 40
10 8b 04 85 a0 f6 ab c0 8b 80 0c b0 b3 c0 f6 44 24 0d 02
EIP: [<c0407462>] xen_iret+0x12/0x2b SS:ESP 0069:eb8d1fe0
general protection fault: 0000 [#2]
---[ end trace ab0d29a492dcd330 ]---
Kernel panic - not syncing: Fatal exception
Pid: 1250, comm: r Tainted: G      D    ---------------
2.6.32-356.el6.i686 #1
Call Trace:
 [<c08476df>] ? panic+0x6e/0x122
 [<c084b63c>] ? oops_end+0xbc/0xd0
 [<c084b260>] ? do_general_protection+0x0/0x210
 [<c084a9b7>] ? error_code+0x73/
-------------

Petr says: "
 I've analysed the bug and I think that xen_iret() cannot cope with
 mangled DS, in this case zeroed out (null selector/descriptor) by either
 xen_failsafe_callback() or RESTORE_REGS because the corresponding LDT
 entry was invalidated by the reproducer. "

Jan took a look at the preliminary patch and came up a fix that solves
this problem:

"This code gets called after all registers other than those handled by
IRET got already restored, hence a null selector in %ds or a non-null
one that got loaded from a code or read-only data descriptor would
cause a kernel mode fault (with the potential of crashing the kernel
as a whole, if panic_on_oops is set)."

The way to fix this is to realize that the we can only relay on the
registers that IRET restores. The two that are guaranteed are the
%cs and %ss as they are always fixed GDT selectors. Also they are
inaccessible from user mode - so they cannot be altered. This is
the approach taken in this patch.

Another alternative option suggested by Jan would be to relay on
the subtle realization that using the %ebp or %esp relative references uses
the %ss segment.  In which case we could switch from using %eax to %ebp and
would not need the %ss over-rides. That would also require one extra
instruction to compensate for the one place where the register is used
as scaled index. However Andrew pointed out that is too subtle and if
further work was to be done in this code-path it could escape folks attention
and lead to accidents.

Reviewed-by: Petr Matousek <pmatouse@redhat.com>
Reported-by: Petr Matousek <pmatouse@redhat.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
PCI/PM: Clean up PME state when removing a device

commit 249bfb83cf8ba658955f0245ac3981d941f746ee upstream.

Devices are added to pci_pme_list when drivers use pci_enable_wake()
or pci_wake_from_d3(), but they aren't removed from the list unless
the driver explicitly disables wakeup.  Many drivers never disable
wakeup, so their devices remain on the list even after they are
removed, e.g., via hotplug.  A subsequent PME poll will oops when
it tries to touch the device.

This patch disables PME# on a device before removing it, which removes
the device from pci_pme_list.  This is safe even if the device never
had PME# enabled.

This oops can be triggered by unplugging a Thunderbolt ethernet adapter
on a Macbook Pro, as reported by Daniel below.

[bhelgaas: changelog]
Reference: http://lkml.kernel.org/r/CAMVG2svG21yiM1wkH4_2pen2n+cr2-Zv7TbH3Gj+8MwevZjDbw@mail.gmail.com
Reported-and-tested-by: Daniel J Blueman <daniel@quora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
igb: Remove artificial restriction on RQDPC stat reading

commit ae1c07a6b7ced6c0c94c99e3b53f4e7856fa8bff upstream.

For some reason the reading of the RQDPC register was being artificially
limited to 4K.  Instead of limiting the value we should read the value and
add the full amount.  Otherwise this can lead to a misleading number of
dropped packets when the actual value is in fact much higher.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Jeff Pieper   <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Vinson Lee <vlee@twitter.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux 3.0.65
printk: fix buffer overflow when calling log_prefix function from call_console_drivers

This patch corrects a buffer overflow in kernels from 3.0 to 3.4 when calling
log_prefix() function from call_console_drivers().

This bug existed in previous releases but has been revealed with commit
162a7e7500f9664636e649ba59defe541b7c2c60 (2.6.39 => 3.0) that made changes
about how to allocate memory for early printk buffer (use of memblock_alloc).
It disappears with commit 7ff9554bb578ba02166071d2d487b7fc7d860d62 (3.4 => 3.5)
that does a refactoring of printk buffer management.

In log_prefix(), the access to "p[0]", "p[1]", "p[2]" or
"simple_strtoul(&p[1], &endp, 10)" may cause a buffer overflow as this
function is called from call_console_drivers by passing "&LOG_BUF(cur_index)"
where the index must be masked to do not exceed the buffer's boundary.

The trick is to prepare in call_console_drivers() a buffer with the necessary
data (PRI field of syslog message) to be safely evaluated in log_prefix().

This patch can be applied to stable kernel branches 3.0.y, 3.2.y and 3.4.y.

Without this patch, one can freeze a server running this loop from shell :
  $ export DUMMY=`cat /dev/urandom | tr -dc '12345AZERTYUIOPQSDFGHJKLMWXCVBNazertyuiopqsdfghjklmwxcvbn' | head -c255`
  $ while true do ; echo $DUMMY > /dev/kmsg ; done

The "server freeze" depends on where memblock_alloc does allocate printk buffer :
if the buffer overflow is inside another kernel allocation the problem may not
be revealed, else the server may hangs up.

Signed-off-by: Alexandre SIMON <Alexandre.Simon@univ-lorraine.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
3.0.66
x86-32, mm: Remove reference to resume_map_numa_kva()

commit bb112aec5ee41427e9b9726e3d57b896709598ed upstream.

Remove reference to removed function resume_map_numa_kva().

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20130131005616.1C79F411@kernel.stglabs.ibm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mm: fix pageblock bitmap allocation

commit 7c45512df987c5619db041b5c9b80d281e26d3db upstream.

Commit c060f943d092 ("mm: use aligned zone start for pfn_to_bitidx
calculation") fixed out calculation of the index into the pageblock
bitmap when a !SPARSEMEM zome was not aligned to pageblock_nr_pages.

However, the _allocation_ of that bitmap had never taken this alignment
requirement into accout, so depending on the exact size and alignment of
the zone, the use of that index could then access past the allocation,
resulting in some very subtle memory corruption.

This was reported (and bisected) by Ingo Molnar: one of his random
config builds would hang with certain very specific kernel command line
options.

In the meantime, commit c060f943d092 has been marked for stable, so this
fix needs to be back-ported to the stable kernels that backported the
commit to use the right alignment.

Bisected-and-tested-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
timeconst.pl: Eliminate Perl warning

commit 63a3f603413ffe82ad775f2d62a5afff87fd94a0 upstream.

defined(@array) is deprecated in Perl and gives off a warning.
Restructure the code to remove that warning.

[ hpa: it would be interesting to revert to the timeconst.bc script.
  It appears that the failures reported by akpm during testing of
  that script was due to a known broken version of make, not a problem
  with bc.  The Makefile rules could probably be restructured to avoid
  the make bug, or it is probably old enough that it doesn't matter. ]

Reported-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
genirq: Avoid deadlock in spurious handling

commit e716efde75267eab919cdb2bef5b2cb77f305326 upstream.

commit 52553ddf(genirq: fix regression in irqfixup, irqpoll)
introduced a potential deadlock by calling the action handler with the
irq descriptor lock held.

Remove the call and let the handling code run even for an interrupt
where only a single action is registered. That matches the goal of
the above commit and avoids the deadlock.

Document the confusing action = desc->action reload in the handling
loop while at it.

Reported-and-tested-by: "Wang, Warner" <warner.wang@hp.com>
Tested-by: Edward Donovan <edward.donovan@numble.net>
Cc: "Wang, Song-Bo (Stoney)" <song-bo.wang@hp.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
posix-cpu-timers: Fix nanosleep task_struct leak

commit e6c42c295e071dd74a66b5a9fcf4f44049888ed8 upstream.

The trinity fuzzer triggered a task_struct reference leak via
clock_nanosleep with CPU_TIMERs. do_cpu_nanosleep() calls
posic_cpu_timer_create(), but misses a corresponding
posix_cpu_timer_del() which leads to the task_struct reference leak.

Reported-and-tested-by: Tommi Rantala <tt.rantala@gmail.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Dave Jones <davej@redhat.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: http://lkml.kernel.org/r/20130215100810.GF4392@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hrtimer: Prevent hrtimer_enqueue_reprogram race

commit b22affe0aef429d657bc6505aacb1c569340ddd2 upstream.

hrtimer_enqueue_reprogram contains a race which could result in
timer.base switch during unlock/lock sequence.

hrtimer_enqueue_reprogram is releasing the lock protecting the timer
base for calling raise_softirq_irqsoff() due to a lock ordering issue
versus rq->lock.

If during that time another CPU calls __hrtimer_start_range_ns() on
the same hrtimer, the timer base might switch, before the current CPU
can lock base->lock again and therefor the unlock_timer_base() call
will unlock the wrong lock.

[ tglx: Added comment and massaged changelog ]

Signed-off-by: Leonid Shatz <leonid.shatz@ravellosystems.com>
Signed-off-by: Izik Eidus <izik.eidus@ravellosystems.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Link: http://lkml.kernel.org/r/1359981217-389-1-git-send-email-izik.eidus@ravellosystems.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ALSA: ali5451: remove irq enabling in pointer callback

commit dacae5a19b4cbe1b5e3a86de23ea74cbe9ec9652 upstream.

snd_ali_pointer function is called with local
interrupts disabled. However it seems very strange to
reenable them in such way.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Denis Efremov <yefremov.denis@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ALSA: rme32.c irq enabling after spin_lock_irq

commit f49a59c4471d81a233e09dda45187cc44fda009d upstream.

According to the other code in this driver and similar
code in rme96 it seems, that spin_lock_irq in
snd_rme32_capture_close function should be paired
with spin_unlock_irq.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Denis Efremov <yefremov.denis@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: set_termios/set_termiox should not return -EINTR

commit 183d95cdd834381c594d3aa801c1f9f9c0c54fa9 upstream.

See https://bugzilla.redhat.com/show_bug.cgi?id=904907
read command causes bash to abort with double free or corruption (out).

A simple test-case from Roman:

	// Compile the reproducer and send sigchld ti that process.
	// EINTR occurs even if SA_RESTART flag is set.

	void handler(int sig)
	{
	}

	main()
	{
	  struct sigaction act;
	  act.sa_handler = handler;
	  act.sa_flags = SA_RESTART;
	  sigaction (SIGCHLD, &act, 0);
	  struct termio ttp;
	  ioctl(0, TCGETA, &ttp);
	  while(1)
	  {
	    if (ioctl(0, TCSETAW, ttp) < 0)
	      {
		if (errno == EINTR)
		{
		  fprintf(stderr, "BUG!"); return(1);
		}
	      }
	  }
	}

Change set_termios/set_termiox to return -ERESTARTSYS to fix this
particular problem.

I didn't dare to change other EINTR's in drivers/tty/, but they look
equally wrong.

Reported-by: Roman Rakus <rrakus@redhat.com>
Reported-by: Lingzhu Xiang <lxiang@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
xen/netback: check correct frag when looking for head frag

When I backported 7d5145d8eb2b "xen/netback: don't leak pages on failure in
xen_netbk_tx_check_gop" to 3.0 (where it became f0457844e605) I somehow picked
up an extraneous hunk breaking this.

Reported-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
xen: Send spinlock IPI to all waiters

commit 76eaca031f0af2bb303e405986f637811956a422 upstream.

There is a loophole between Xen's current implementation of
pv-spinlocks and the scheduler. This was triggerable through
a testcase until v3.6 changed the TLB flushing code. The
problem potentially is still there just not observable in the
same way.

What could happen was (is):

1. CPU n tries to schedule task x away and goes into a slow
   wait for the runq lock of CPU n-# (must be one with a lower
   number).
2. CPU n-#, while processing softirqs, tries to balance domains
   and goes into a slow wait for its own runq lock (for updating
   some records). Since this is a spin_lock_irqsave in softirq
   context, interrupts will be re-enabled for the duration of
   the poll_irq hypercall used by Xen.
3. Before the runq lock of CPU n-# is unlocked, CPU n-1 receives
   an interrupt (e.g. endio) and when processing the interrupt,
   tries to wake up task x. But that is in schedule and still
   on_cpu, so try_to_wake_up goes into a tight loop.
4. The runq lock of CPU n-# gets unlocked, but the message only
   gets sent to the first waiter, which is CPU n-# and that is
   busily stuck.
5. CPU n-# never returns from the nested interruption to take and
   release the lock because the scheduler uses a busy wait.
   And CPU n never finishes the task migration because the unlock
   notification only went to CPU n-#.

To avoid this and since the unlocking code has no real sense of
which waiter is best suited to grab the lock, just send the IPI
to all of them. This causes the waiters to return from the hyper-
call (those not interrupted at least) and do active spinlocking.

BugLink: http://bugs.launchpad.net/bugs/1011792

Acked-by: Jan Beulich <JBeulich@suse.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Driver core: treat unregistered bus_types as having no devices

commit 4fa3e78be7e985ca814ce2aa0c09cbee404efcf7 upstream.

A bus_type has a list of devices (klist_devices), but the list and the
subsys_private structure that contains it are not initialized until the
bus_type is registered with bus_register().

The panic/reboot path has fixups that look up devices in pci_bus_type.  If
we panic before registering pci_bus_type, the bus_type exists but the list
does not, so mach_reboot_fixups() trips over a null pointer and panics
again:

    mach_reboot_fixups
      pci_get_device
        ..
          bus_find_device(&pci_bus_type, ...)
            bus->p is NULL

Joonsoo reported a problem when panicking before PCI was initialized.
I think this patch should be sufficient to replace the patch he posted
here: https://lkml.org/lkml/2012/12/28/75 ("[PATCH] x86, reboot: skip
reboot_fixups in early boot phase")

Reported-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mm: mmu_notifier: have mmu_notifiers use a global SRCU so they may safely schedule

commit 21a92735f660eaecf69a6f2e777f18463760ec32 upstream.

With an RCU based mmu_notifier implementation, any callout to
mmu_notifier_invalidate_range_{start,end}() or
mmu_notifier_invalidate_page() would not be allowed to call schedule()
as that could potentially allow a modification to the mmu_notifier
structure while it is currently being used.

Since srcu allocs 4 machine words per instance per cpu, we may end up
with memory exhaustion if we use srcu per mm.  So all mms share a global
srcu.  Note that during large mmu_notifier activity exit & unregister
paths might hang for longer periods, but it is tolerable for current
mmu_notifier clients.

Signed-off-by: Sagi Grimberg <sagig@mellanox.co.il>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Haggai Eran <haggaie@mellanox.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>