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  1. 30 1月, 2013 18 次提交
  3. 29 1月, 2013 1 次提交
  5. 23 1月, 2013 1 次提交
    • O
      ptrace: ensure arch_ptrace/ptrace_request can never race with SIGKILL · 9899d11f
      由 Oleg Nesterov 提交于 
      putreg() assumes that the tracee is not running and pt_regs_access() can
safely play with its stack.  However a killed tracee can return from
ptrace_stop() to the low-level asm code and do RESTORE_REST, this means
that debugger can actually read/modify the kernel stack until the tracee
does SAVE_REST again.

set_task_blockstep() can race with SIGKILL too and in some sense this
race is even worse, the very fact the tracee can be woken up breaks the
logic.

As Linus suggested we can clear TASK_WAKEKILL around the arch_ptrace()
call, this ensures that nobody can ever wakeup the tracee while the
debugger looks at it.  Not only this fixes the mentioned problems, we
can do some cleanups/simplifications in arch_ptrace() paths.

Probably ptrace_unfreeze_traced() needs more callers, for example it
makes sense to make the tracee killable for oom-killer before
access_process_vm().

While at it, add the comment into may_ptrace_stop() to explain why
ptrace_stop() still can't rely on SIGKILL and signal_pending_state().
Reported-by: NSalman Qazi <sqazi@google.com>
Reported-by: NSuleiman Souhlal <suleiman@google.com>
Suggested-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9899d11f
  7. 17 1月, 2013 1 次提交
    • A
      xen: Fix stack corruption in xen_failsafe_callback for 32bit PVOPS guests. · 9174adbe
      由 Andrew Cooper 提交于 
      This fixes CVE-2013-0190 / XSA-40

There has been an error on the xen_failsafe_callback path for failed
iret, which causes the stack pointer to be wrong when entering the
iret_exc error path.  This can result in the kernel crashing.

In the classic kernel case, the relevant code looked a little like:

        popl %eax      # Error code from hypervisor
        jz 5f
        addl $16,%esp
        jmp iret_exc   # Hypervisor said iret fault
5:      addl $16,%esp
                       # Hypervisor said segment selector fault

Here, there are two identical addls on either option of a branch which
appears to have been optimised by hoisting it above the jz, and
converting it to an lea, which leaves the flags register unaffected.

In the PVOPS case, the code looks like:

        popl_cfi %eax         # Error from the hypervisor
        lea 16(%esp),%esp     # Add $16 before choosing fault path
        CFI_ADJUST_CFA_OFFSET -16
        jz 5f
        addl $16,%esp         # Incorrectly adjust %esp again
        jmp iret_exc

It is possible unprivileged userspace applications to cause this
behaviour, for example by loading an LDT code selector, then changing
the code selector to be not-present.  At this point, there is a race
condition where it is possible for the hypervisor to return back to
userspace from an interrupt, fault on its own iret, and inject a
failsafe_callback into the kernel.

This bug has been present since the introduction of Xen PVOPS support
in commit 5ead97c8 (xen: Core Xen implementation), in 2.6.23.
Signed-off-by: NFrediano Ziglio <frediano.ziglio@citrix.com>
Signed-off-by: NAndrew Cooper <andrew.cooper3@citrix.com>
Cc: stable@vger.kernel.org
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
      9174adbe
  9. 14 1月, 2013 2 次提交
  11. 12 1月, 2013 1 次提交
    • J
      x86/Sandy Bridge: reserve pages when integrated graphics is present · a9acc536
      由 Jesse Barnes 提交于 
      SNB graphics devices have a bug that prevent them from accessing certain
memory ranges, namely anything below 1M and in the pages listed in the
table.  So reserve those at boot if set detect a SNB gfx device on the
CPU to avoid GPU hangs.

Stephane Marchesin had a similar patch to the page allocator awhile
back, but rather than reserving pages up front, it leaked them at
allocation time.

[ hpa: made a number of stylistic changes, marked arrays as static
  const, and made less verbose; use "memblock=debug" for full
  verbosity. ]
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
      a9acc536
  13. 10 1月, 2013 1 次提交
    • D
      perf x86: revert 20b279 - require exclude_guest to use PEBS - kernel side · a706d965
      由 David Ahern 提交于 
      This patch is brought to you by the letter 'H'.

Commit 20b279 breaks compatiblity with older perf binaries when run with
precise modifier (:p or :pp) by requiring the exclude_guest attribute to be
set. Older binaries default exclude_guest to 0 (ie., wanting guest-based
samples) unless host only profiling is requested (:H modifier). The workaround
for older binaries is to add H to the modifier list (e.g., -e cycles:ppH -
toggles exclude_guest to 1). This was deemed unacceptable by Linus:

https://lkml.org/lkml/2012/12/12/570

Between family in town and the fresh snow in Breckenridge there is no time left
to be working on the proper fix for this over the holidays. In the New Year I
have more pressing problems to resolve -- like some memory leaks in perf which
are proving to be elusive -- although the aforementioned snow is probably why
they are proving to be elusive. Either way I do not have any spare time to work
on this and from the time I have managed to spend on it the solution is more
difficult than just moving to a new exclude_guest flag (does not work) or
flipping the logic to include_guest (which is not as trivial as one would
think).

So, two options: silently force exclude_guest on as suggested by Gleb which
means no impact to older perf binaries or revert the original patch which
caused the breakage.

This patch does the latter -- reverts the original patch that introduced the
regression. The problem can be revisited in the future as time allows.
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <robert.richter@amd.com>
Link: http://lkml.kernel.org/r/1356749767-17322-1-git-send-email-dsahern@gmail.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      a706d965
  15. 04 1月, 2013 1 次提交
    • G
      X86: drivers: remove __dev* attributes. · a18e3690
      由 Greg Kroah-Hartman 提交于 
      CONFIG_HOTPLUG is going away as an option.  As a result, the __dev*
markings need to be removed.

This change removes the use of __devinit, __devexit_p, __devinitconst,
and __devexit from these drivers.

Based on patches originally written by Bill Pemberton, but redone by me
in order to handle some of the coding style issues better, by hand.

Cc: Bill Pemberton <wfp5p@virginia.edu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Daniel Drake <dsd@laptop.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      a18e3690
  17. 20 12月, 2012 3 次提交
  19. 18 12月, 2012 2 次提交
    • L
      Add rcu user eqs exception hooks for async page fault · 9b132fbe
      由 Li Zhong 提交于 
      This patch adds user eqs exception hooks for async page fault page not
present code path, to exit the user eqs and re-enter it as necessary.

Async page fault is different from other exceptions that it may be
triggered from idle process, so we still need rcu_irq_enter() and
rcu_irq_exit() to exit cpu idle eqs when needed, to protect the code
that needs use rcu.

As Frederic pointed out it would be safest and simplest to protect the
whole kvm_async_pf_task_wait(). Otherwise, "we need to check all the
code there deeply for potential RCU uses and ensure it will never be
extended later to use RCU.".

However, We'd better re-enter the cpu idle eqs if we get the exception
in cpu idle eqs, by calling rcu_irq_exit() before native_safe_halt().

So the patch does what Frederic suggested for rcu_irq_*() API usage
here, except that I moved the rcu_irq_*() pair originally in
do_async_page_fault() into kvm_async_pf_task_wait().

That's because, I think it's better to have rcu_irq_*() pairs to be in
one function ( rcu_irq_exit() after rcu_irq_enter() ), especially here,
kvm_async_pf_task_wait() has other callers, which might cause
rcu_irq_exit() be called without a matching rcu_irq_enter() before it,
which is illegal if the cpu happens to be in rcu idle state.
Signed-off-by: NLi Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: NGleb Natapov <gleb@redhat.com>
      9b132fbe
    • H
      x86, 386 removal: Remove support for IRQ 13 FPU error reporting · bc3eba60
      由 H. Peter Anvin 提交于 
      Remove support for FPU error reporting via IRQ 13, as opposed to
exception 16 (#MF).  One last remnant of i386 gone.
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Cc: Alan Cox <alan@linux.intel.com>
      bc3eba60
  21. 16 12月, 2012 1 次提交
  23. 13 12月, 2012 1 次提交
  25. 12 12月, 2012 3 次提交
  27. 08 12月, 2012 1 次提交
  29. 07 12月, 2012 2 次提交
  31. 06 12月, 2012 1 次提交