linux-kernel - [PATCH] posix-timers: Prevent broadcast signals

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Message-Id: <20180427093426.13321-1-bigeasy@linutronix.de>
Date:   Fri, 27 Apr 2018 11:34:26 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     "Eric W . Biederman " <ebiederm@...ssion.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH] posix-timers: Prevent broadcast signals

From: Thomas Gleixner <tglx@...utronix.de>

Posix timers should not send broadcast signals and kernel only
signals. Prevent it.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 kernel/time/posix-timers.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index b6899b5060bd..4c4cbebb0d71 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -435,6 +435,7 @@ static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
 static struct pid *good_sigevent(sigevent_t * event)
 {
 	struct task_struct *rtn = current->group_leader;
+	int sig = event->sigev_signo;
 
 	switch (event->sigev_notify) {
 	case SIGEV_SIGNAL | SIGEV_THREAD_ID:
@@ -444,7 +445,8 @@ static struct pid *good_sigevent(sigevent_t * event)
 		/* FALLTHRU */
 	case SIGEV_SIGNAL:
 	case SIGEV_THREAD:
-		if (event->sigev_signo <= 0 || event->sigev_signo > SIGRTMAX)
+		if (sig <= 0 || sig > SIGRTMAX ||
+		    sig_kernel_only(sig) || sig_kernel_coredump(sig))
 			return NULL;
 		/* FALLTHRU */
 	case SIGEV_NONE:
-- 
2.17.0