We need to check for stack overflow only when the signal is on stack.
So we can improve the patch "http://lkml.org/lkml/2007/11/27/101" as following.
Signed-off-by: Shi Weihua <shiwh@cn.fujitsu.com>
---
The previous patch has a comment mistake. Now I correct it.
---
--- linux-2.6.25-rc2.orig/arch/x86/kernel/signal_32.c 2008-02-16 04:57:20.000000000 +0800
+++ linux-2.6.25-rc2/arch/x86/kernel/signal_32.c 2008-02-19 09:55:59.000000000 +0800
@@ -299,17 +299,21 @@ get_sigframe(struct k_sigaction *ka, str
/* Default to using normal stack */
sp = regs->sp;
- /*
- * 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)
+ int onstack = sas_ss_flags(sp);
+
+ if (onstack == 0)
sp = current->sas_ss_sp + current->sas_ss_size;
+ else if (onstack == SS_ONSTACK) {
+ /*
+ * 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 (!likely(on_sig_stack(sp - frame_size)))
+ return (void __user *) -1L;
+ }
}
/* This is the legacy signal stack switching. */
--
