linux-kernel - [PATCH 2/4] score: signal: fix sigaltstack check

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Date:	Sun, 31 Jan 2016 22:14:26 +0300
From:	Stas Sergeev <stsp@...t.ru>
To:	Linux kernel <linux-kernel@...r.kernel.org>
Cc:	Andy Lutomirski <luto@...capital.net>,
	Chen Liqin <liqin.linux@...il.com>,
	Lennox Wu <lennox.wu@...il.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Andrew Morton <akpm@...ux-foundation.org>,
	James Hogan <james.hogan@...tec.com>
Subject: [PATCH 2/4] score: signal: fix sigaltstack check


Currently get_sigframe() checks only
(ka->sa.sa_flags & SA_ONSTACK) && (!on_sig_stack(sp))
to determine whether the switch to sigaltstack is needed.
It forgets to checks whether the sigaltstack was previously set.

This patch replaces the !on_sig_stack(sp) with the standard check
sas_ss_flags(sp) == 0
that takes into account both conditions: it succeeds only if the
sigaltstack is enabled but currently not active.

CC: Andy Lutomirski <luto@...capital.net>
CC: linux-kernel@...r.kernel.org
CC: Chen Liqin <liqin.linux@...il.com>
CC: Lennox Wu <lennox.wu@...il.com>
CC: Michael Ellerman <mpe@...erman.id.au>
CC: Andrew Morton <akpm@...ux-foundation.org>
CC: James Hogan <james.hogan@...tec.com>

Signed-off-by: Stas Sergeev <stsp@...rs.sourceforge.net>
---
  arch/score/kernel/signal.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/score/kernel/signal.c b/arch/score/kernel/signal.c
index e381c8c..bd1c7c8 100644
--- a/arch/score/kernel/signal.c
+++ b/arch/score/kernel/signal.c
@@ -127,7 +127,7 @@ static void __user *get_sigframe(struct k_sigaction *ka,
      sp -= 32;

      /* This is the X/Open sanctioned signal stack switching.  */
-    if ((ka->sa.sa_flags & SA_ONSTACK) && (!on_sig_stack(sp)))
+    if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
          sp = current->sas_ss_sp + current->sas_ss_size;

      return (void __user*)((sp - frame_size) & ~7);
-- 
2.5.0