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| author | Ingo Molnar <mingo@elte.hu> | 2009-01-20 09:31:49 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-01-21 09:43:18 +0100 |
| commit | 552b8aa4d1edcc1c764ff6f61a7686347a2d1827 (patch) | |
| tree | cdebda18ea3360461358127091859610be2acf01 /arch/x86/kernel/signal.c | |
| parent | e0a96129db574d6365e3439d16d88517c437ab33 (diff) | |
Revert "x86: signal: change type of paramter for sys_rt_sigreturn()"
This reverts commit 4217458dafaa57d8e26a46f5d05ab8c53cf64191.
Justin Madru bisected this commit, it was causing weird Firefox
crashes.
The reason is that GCC mis-optimizes (re-uses) the on-stack parameters of
the calling frame, which corrupts the syscall return pt_regs state and
thus corrupts user-space register state.
So we go back to the slightly less clean but more optimization-safe
method of getting to pt_regs. Also add a comment to explain this.
Resolves: http://bugzilla.kernel.org/show_bug.cgi?id=12505
Reported-and-bisected-by: Justin Madru <jdm64@gawab.com>
Tested-by: Justin Madru <jdm64@gawab.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/signal.c')
| -rw-r--r-- | arch/x86/kernel/signal.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 89bb7668041d..df0587f24c54 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -632,9 +632,16 @@ badframe: } #ifdef CONFIG_X86_32 -asmlinkage int sys_rt_sigreturn(struct pt_regs regs) +/* + * Note: do not pass in pt_regs directly as with tail-call optimization + * GCC will incorrectly stomp on the caller's frame and corrupt user-space + * register state: + */ +asmlinkage int sys_rt_sigreturn(unsigned long __unused) { - return do_rt_sigreturn(®s); + struct pt_regs *regs = (struct pt_regs *)&__unused; + + return do_rt_sigreturn(regs); } #else /* !CONFIG_X86_32 */ asmlinkage long sys_rt_sigreturn(struct pt_regs *regs) |