[PATCH] fix incorrect SA_ONSTACK behaviour for 64-bit processes

- When setting a sighandler using sigaction() call, if the flag
  SA_ONSTACK is set and no alternate stack is provided via sigaltstack(),
  the kernel still try to install the alternate stack.  This behavior is
  the opposite of the one which is documented in Single Unix Specifications
  V3.

- Also when setting an alternate stack using sigaltstack() with the flag
  SS_DISABLE, the kernel try to install the alternate stack on signal
  delivery.

These two use cases makes the process crash at signal delivery.

Signed-off-by: Laurent Meyer <meyerlau@fr.ibm.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: David Howells <dhowells@redhat.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp>
Cc: Chris Zankel <chris@zankel.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/alpha/kernel/signal.c b/arch/alpha/kernel/signal.c
index 2e45e8604e3..741da0945dc 100644
--- a/arch/alpha/kernel/signal.c
+++ b/arch/alpha/kernel/signal.c
@@ -375,7 +375,7 @@ give_sigsegv:
 static inline void __user *
 get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
 {
-	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp))
+	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp))
 		sp = current->sas_ss_sp + current->sas_ss_size;
 
 	return (void __user *)((sp - frame_size) & -32ul);