diff options
| author | Suresh Siddha <suresh.b.siddha@intel.com> | 2008-09-30 17:56:13 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2008-10-08 20:22:55 -0700 |
| commit | 42f5a87ed3db2b49da7374e61ed4a7aa5f46e626 (patch) | |
| tree | 4f6585b02782f6b73b2ab02b9ddadafdc3460107 /include | |
| parent | 568fc52e4917a0bfb0ac8b54eb8636f9e51886c1 (diff) | |
x64, fpu: fix possible FPU leakage in error conditions
[Upstream commit: 6ffac1e90a17ea0aded5c581204397421eec91b6]
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: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include')
| -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 6d3b21063419..56d00e31aec0 100644 --- a/include/asm-x86/i387.h +++ b/include/asm-x86/i387.h @@ -63,8 +63,6 @@ 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; } |