diff options
| author | Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> | 2009-03-19 10:56:29 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-03-20 19:01:31 +0100 |
| commit | 14fc9fbc700dc95b4f46ebd588169324fe6deff8 (patch) | |
| tree | db11b6437bc9600295f415ab4d087da861ecbe97 /arch/x86/kernel/signal.c | |
| parent | 7f00a2495bf5b98b097c47be5d6e2d4114ec39bf (diff) | |
x86: signal: check signal stack overflow properly
Impact: cleanup
Check alternate signal stack overflow with proper stack pointer.
The stack pointer of the next signal frame is different if that
task has i387 state.
On x86_64, redzone would be included.
No need to check SA_ONSTACK if we're already using alternate signal stack.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Cc: Roland McGrath <roland@redhat.com>
LKML-Reference: <49C2874D.3080002@ct.jp.nec.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 | 48 |
1 files changed, 27 insertions, 21 deletions
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index d2cc6428c587..dfcc74ab0ab6 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -211,31 +211,27 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, { /* Default to using normal stack */ unsigned long sp = regs->sp; + int onsigstack = on_sig_stack(sp); #ifdef CONFIG_X86_64 /* redzone */ sp -= 128; #endif /* CONFIG_X86_64 */ - /* - * If we are on the alternate signal stack and would overflow it, don't. - * Return an always-bogus address instead so we will die with SIGSEGV. - */ - if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size))) - return (void __user *) -1L; - - /* This is the X/Open sanctioned signal stack switching. */ - if (ka->sa.sa_flags & SA_ONSTACK) { - if (sas_ss_flags(sp) == 0) - sp = current->sas_ss_sp + current->sas_ss_size; - } else { + if (!onsigstack) { + /* This is the X/Open sanctioned signal stack switching. */ + if (ka->sa.sa_flags & SA_ONSTACK) { + if (sas_ss_flags(sp) == 0) + sp = current->sas_ss_sp + current->sas_ss_size; + } else { #ifdef CONFIG_X86_32 - /* This is the legacy signal stack switching. */ - if ((regs->ss & 0xffff) != __USER_DS && - !(ka->sa.sa_flags & SA_RESTORER) && - ka->sa.sa_restorer) - sp = (unsigned long) ka->sa.sa_restorer; + /* This is the legacy signal stack switching. */ + if ((regs->ss & 0xffff) != __USER_DS && + !(ka->sa.sa_flags & SA_RESTORER) && + ka->sa.sa_restorer) + sp = (unsigned long) ka->sa.sa_restorer; #endif /* CONFIG_X86_32 */ + } } if (used_math()) { @@ -244,12 +240,22 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, sp = round_down(sp, 64); #endif /* CONFIG_X86_64 */ *fpstate = (void __user *)sp; - - if (save_i387_xstate(*fpstate) < 0) - return (void __user *)-1L; } - return (void __user *)align_sigframe(sp - frame_size); + sp = align_sigframe(sp - frame_size); + + /* + * If we are on the alternate signal stack and would overflow it, don't. + * Return an always-bogus address instead so we will die with SIGSEGV. + */ + if (onsigstack && !likely(on_sig_stack(sp))) + return (void __user *)-1L; + + /* save i387 state */ + if (used_math() && save_i387_xstate(*fpstate) < 0) + return (void __user *)-1L; + + return (void __user *)sp; } #ifdef CONFIG_X86_32 |