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| author | Suresh Siddha <suresh.b.siddha@intel.com> | 2008-07-24 18:07:56 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-07-26 16:37:04 +0200 |
| commit | 6ffac1e90a17ea0aded5c581204397421eec91b6 (patch) | |
| tree | c5ae5b695f1306f5415b5bf3968b4fcf69e823a1 /include/asm-x86 | |
| parent | 024e8ac04453b3525448c31ef39848cf675ba6db (diff) | |
| download | linux-0-day-6ffac1e90a17ea0aded5c581204397421eec91b6.tar.gz linux-0-day-6ffac1e90a17ea0aded5c581204397421eec91b6.tar.xz | |
x64, fpu: fix possible FPU leakage in error conditions
On Thu, Jul 24, 2008 at 03:43:44PM -0700, Linus Torvalds wrote:
> So how about this patch as a starting point? This is the RightThing(tm) to
> do regardless, and if it then makes it easier to do some other cleanups,
> we should do it first. What do you think?
restore_fpu_checking() calls init_fpu() in error conditions.
While this is wrong(as our main intention is to clear the fpu state of
the thread), this was benign before commit 92d140e21f1 ("x86: fix taking
DNA during 64bit sigreturn").
Post commit 92d140e21f1, live FPU registers may not belong to this
process at this error scenario.
In the error condition for restore_fpu_checking() (especially during the
64bit signal return), we are doing init_fpu(), which saves the live FPU
register state (possibly belonging to some other process context) into
the thread struct (through unlazy_fpu() in init_fpu()). This is wrong
and can leak the FPU data.
For the signal handler restore error condition in restore_i387(), clear
the fpu state present in the thread struct(before ultimately sending a
SIGSEGV for badframe).
For the paranoid error condition check in math_state_restore(), send a
SIGSEGV, if we fail to restore the state.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: <stable@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/asm-x86')
| -rw-r--r-- | include/asm-x86/i387.h | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/include/asm-x86/i387.h b/include/asm-x86/i387.h index 96fa8449ff11d..0048fb77afc45 100644 --- a/include/asm-x86/i387.h +++ b/include/asm-x86/i387.h @@ -62,8 +62,6 @@ static inline int restore_fpu_checking(struct i387_fxsave_struct *fx) #else : [fx] "cdaSDb" (fx), "m" (*fx), "0" (0)); #endif - if (unlikely(err)) - init_fpu(current); return err; } |