From: Oleg Nesterov <oleg@redhat.com>
Date: Fri, 17 Nov 2017 23:30:04 +0000 (-0800)
Subject: kernel/signal.c: protect the SIGNAL_UNKILLABLE tasks from !sig_kernel_only() signals
X-Git-Tag: v3.18.92~42
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=64c64936d42b910a4f3f74f00f420b6fa06792c9;p=thirdparty%2Fkernel%2Fstable.git

kernel/signal.c: protect the SIGNAL_UNKILLABLE tasks from !sig_kernel_only() signals

commit ac25385089f673560867eb5179228a44ade0cfc1 upstream.

Change sig_task_ignored() to drop the SIG_DFL && !sig_kernel_only()
signals even if force == T.  This simplifies the next change and this
matches the same check in get_signal() which will drop these signals
anyway.

Link: http://lkml.kernel.org/r/20171103184227.GC21036@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Tested-by: Kyle Huey <me@kylehuey.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/kernel/signal.c b/kernel/signal.c
index b956332ded424..63602c815a587 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -72,7 +72,7 @@ static int sig_task_ignored(struct task_struct *t, int sig, bool force)
 	handler = sig_handler(t, sig);
 
 	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
-			handler == SIG_DFL && !force)
+	    handler == SIG_DFL && !(force && sig_kernel_only(sig)))
 		return 1;
 
 	return sig_handler_ignored(handler, sig);