Re: Signal handling possibly wrong

[Chris Wright <chrisw@osdl.org>]

* Steven Rostedt (rostedt@goodmis.org) wrote:
> Where, sa_mask is _ignored_ if NODEFER is set. (I now have woken up!).
> The attached program shows that the sa_mask is indeed ignored when
> SA_NODEFER is set.
> 
> Now the real question is... Is this a bug?

That's not correct w.r.t. SUSv3.  sa_mask should be always used and
SA_NODEFER is just whether or not to add that signal in.

SA_NODEFER
    [XSI] If set and sig is caught, sig shall not be added to the thread's
    signal mask on entry to the signal handler unless it is included in
    sa_mask. Otherwise, sig shall always be added to the thread's signal
    mask on entry to the signal handler.

Brodo, is this what you mean?

thanks,
-chris
--

Subject: [PATCH] fix SA_NODEFER signals to honor sa_mask

When receiving SA_NODEFER signal, kernel was inapproriately not applying
the sa_mask.  As pointed out by Brodo Stroesser.

Signed-off-by: Chris Wright <chrisw@osdl.org>
---

diff --git a/arch/i386/kernel/signal.c b/arch/i386/kernel/signal.c
--- a/arch/i386/kernel/signal.c
+++ b/arch/i386/kernel/signal.c
@@ -577,13 +577,12 @@ handle_signal(unsigned long sig, siginfo
 	else
 		ret = setup_frame(sig, ka, oldset, regs);
 
-	if (ret && !(ka->sa.sa_flags & SA_NODEFER)) {
-		spin_lock_irq(&current->sighand->siglock);
-		sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	spin_lock_irq(&current->sighand->siglock);
+	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (ret && !(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked,sig);
-		recalc_sigpending();
-		spin_unlock_irq(&current->sighand->siglock);
-	}
+	recalc_sigpending();
+	spin_unlock_irq(&current->sighand->siglock);
 
 	return ret;
 }