[PATCH 2/3] protect the SIGNAL_UNKILLABLE tasks from !sig_kernel_only() signals

From: Oleg Nesterov <oleg@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>
Cc: security@kernel.org, "Robert O'Callahan" <robert@ocallahan.org>,
	Kees Cook <keescook@chromium.org>,
	Andy Lutomirski <luto@kernel.org>,
	Dmitry Vyukov <dvyukov@google.com>, Kyle Huey <me@kylehuey.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH 2/3] protect the SIGNAL_UNKILLABLE tasks from !sig_kernel_only() signals
Date: Fri, 3 Nov 2017 19:42:27 +0100	[thread overview]
Message-ID: <20171103184227.GC21036@redhat.com> (raw)
In-Reply-To: <20171103184144.GA21036@redhat.com>

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.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 kernel/signal.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index b9aebe1..8fc0182 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -78,7 +78,7 @@ 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);
-- 
2.5.0
