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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 | |
| parent | x86: use early clobbers in usercopy*.c (diff) | |
| download | linux-552b8aa4d1edcc1c764ff6f61a7686347a2d1827.tar.xz linux-552b8aa4d1edcc1c764ff6f61a7686347a2d1827.zip | |
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')
| -rw-r--r-- | arch/x86/include/asm/syscalls.h | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/signal.c | 11 |
2 files changed, 10 insertions, 3 deletions
diff --git a/arch/x86/include/asm/syscalls.h b/arch/x86/include/asm/syscalls.h index 9c6797c3e56c..c0b0bda754ee 100644 --- a/arch/x86/include/asm/syscalls.h +++ b/arch/x86/include/asm/syscalls.h @@ -40,7 +40,7 @@ asmlinkage int sys_sigaction(int, const struct old_sigaction __user *, struct old_sigaction __user *); asmlinkage int sys_sigaltstack(unsigned long); asmlinkage unsigned long sys_sigreturn(unsigned long); -asmlinkage int sys_rt_sigreturn(struct pt_regs); +asmlinkage int sys_rt_sigreturn(unsigned long); /* kernel/ioport.c */ asmlinkage long sys_iopl(unsigned long); 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) |