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authorHiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>2009-03-19 10:56:29 -0700
committerIngo Molnar <mingo@elte.hu>2009-03-20 19:01:31 +0100
commit14fc9fbc700dc95b4f46ebd588169324fe6deff8 (patch)
treedb11b6437bc9600295f415ab4d087da861ecbe97 /arch/x86/kernel/signal.c
parent7f00a2495bf5b98b097c47be5d6e2d4114ec39bf (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.c48
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