[IA64] signal(ia64_ia32): add a signal stack overflow check

The similar check has been added to x86_32(i386) in commit
id 83bd01024b1fdfc41d9b758e5669e80fca72df66.
So we add this check to ia64_ia32 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 <shiwh@cn.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/arch/ia64/ia32/ia32_signal.c b/arch/ia64/ia32/ia32_signal.c
index 85e82f32e480..256a7faeda07 100644
--- a/arch/ia64/ia32/ia32_signal.c
+++ b/arch/ia64/ia32/ia32_signal.c
@@ -766,8 +766,19 @@ get_sigframe (struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 
         /* This is the X/Open sanctioned signal stack switching.  */
         if (ka->sa.sa_flags & SA_ONSTACK) {
-                if (!on_sig_stack(esp))
+                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;
+                }
         }
         /* Legacy stack switching not supported */