From 0f8f308925ebe0480bd9831d32963ee0b885e24b Mon Sep 17 00:00:00 2001
From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Date: Thu, 26 Mar 2009 10:03:08 -0700
Subject: [PATCH] x86: signal: check sas_ss_size instead of sas_ss_flags()
Impact: fix redundant and incorrect check
Oleg Nesterov noticed wrt commit:
14fc9fb: x86: signal: check signal stack overflow properly
>> No need to check SA_ONSTACK if we're already using alternate signal stack.
>
> Yes, but this also mean that we don't need sas_ss_flags() under
> "if (!onsigstack)",
Checking on_sig_stack() in sas_ss_flags() at get_sigframe() is redundant
and not correct on 64 bit. To check sas_ss_size is enough.
Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Cc: roland@redhat.com
LKML-Reference: <49CBB54C.5080201@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/signal.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index dfcc74ab0ab6..14425166b8e3 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -221,7 +221,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
if (!onsigstack) {
/* This is the X/Open sanctioned signal stack switching. */
if (ka->sa.sa_flags & SA_ONSTACK) {
- if (sas_ss_flags(sp) == 0)
+ if (current->sas_ss_size)
sp = current->sas_ss_sp + current->sas_ss_size;
} else {
#ifdef CONFIG_X86_32
--
2.34.1