Matthew Wilcox wrote::
> On Mon, Feb 18, 2008 at 06:26:23PM +0800, Shi Weihua wrote:
>> + if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
>> + new_rbs = (current->sas_ss_sp +
>> + sizeof(long) - 1) & ~(sizeof(long) -
>> 1);
>
> I know you're only moving this code, but how about fixing it to use
> ALIGN at the same time?
>
> + if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
> + new_rbs = ALIGN(current->sas_ss_sp,
> + sizeof(long));
>
Of course,we can improve the code by ALIGN.
---
The similar check has been added to x86_32(i386) in commit
id 83bd01024b1fdfc41d9b758e5669e80fca72df66.
So we add this check to ia64 and improve it a liitle bit in that
we need to check for stack overflow only when the signal is on stack.
Signed-off-by: Shi Weihua <[EMAIL PROTECTED]>
---
--- linux-2.6.25-rc2.orig/arch/ia64/kernel/signal.c 2008-02-16
04:57:20.000000000 +0800
+++ linux-2.6.25-rc2/arch/ia64/kernel/signal.c 2008-02-19 09:57:05.000000000
+0800
@@ -342,15 +342,33 @@ setup_frame (int sig, struct k_sigaction
new_sp = scr->pt.r12;
tramp_addr = (unsigned long) __kernel_sigtramp;
- if ((ka->sa.sa_flags & SA_ONSTACK) && sas_ss_flags(new_sp) == 0) {
- new_sp = current->sas_ss_sp + current->sas_ss_size;
- /*
- * We need to check for the register stack being on the signal
stack
- * separately, because it's switched separately (memory stack
is switched
- * in the kernel, register stack is switched in the signal
trampoline).
- */
- if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
- new_rbs = (current->sas_ss_sp + sizeof(long) - 1) &
~(sizeof(long) - 1);
+ if (ka->sa.sa_flags & SA_ONSTACK) {
+ int onstack = sas_ss_flags(new_sp);
+
+ if (onstack == 0) {
+ new_sp = current->sas_ss_sp + current->sas_ss_size;
+ /*
+ * We need to check for the register stack being on the
+ * signal stack separately, because it's switched
+ * separately (memory stack is switched in the kernel,
+ * register stack is switched in the signal trampoline).
+ */
+ if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
+ new_rbs = ALIGN(current->sas_ss_sp,
+ sizeof(long));
+ } else if (onstack == SS_ONSTACK) {
+ unsigned long check_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.
+ */
+ check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN;
+ if (!likely(on_sig_stack(check_sp)))
+ return force_sigsegv_info(sig, (void __user *)
+ check_sp);
+ }
}
frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN);
--
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