Roland McGrath wrote::
>>> Thank you for your detailed explanation and patch. I tested your
>>> patch, unfortunately it can not stop all kinds of overflow.
>> [...]
>>> So, the patch I posted is still needed
>> thanks, i've picked up your fix for x86.git, for 2.6.25 merging.
>
> I just explained that not all overflows would be caught and that doing so
> would violate the semantics of e.g. longjmp. I don't see how the patch
> you've included now doesn't still have all those problems. I think it's wrong.
>
I am sorry, i don't understand how this is related to the semantics of e.g. longjmp.
But, i am sure my patch solves all overflows. Ingo's patch can't catch the overflow
which is caught by "int i[1000];" in the handler function.
Do you have more idea for me? Thanks.
Regards
Shi Weihua
By the way, I think Ingo's patch can be improved.
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Shi Weihua <[email protected]>
---
--- linux-2.6.24-rc4-git1.orig/arch/x86/kernel/signal_32.c 2007-12-04 12:26:10.000000000 +0800
+++ linux-2.6.24-rc4-git1/arch/x86/kernel/signal_32.c 2007-12-05 11:13:56.000000000 +0800
@@ -297,8 +297,17 @@ get_sigframe(struct k_sigaction *ka, str
/* This is the X/Open sanctioned signal stack switching. */
if (ka->sa.sa_flags & SA_ONSTACK) {
- if (sas_ss_flags(esp) == 0)
+ int onstack = sas_ss_flags(esp);
+ if (onstack == 0)
esp = 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(esp - frame_size)))
+ return (void __user *) -1L;
+ }
}
/* This is the legacy signal stack switching. */
--
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