4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Thomas Gleixner <t...@linutronix.de> commit c1a9eeb938b5433947e5ea22f89baff3182e7075 upstream. When a disfunctional timer, e.g. dummy timer, is installed, the tick core tries to setup the broadcast timer. If no broadcast device is installed, the kernel crashes with a NULL pointer dereference in tick_broadcast_setup_oneshot() because the function has no sanity check. Reported-by: Mason <slash....@free.fr> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Cc: Mark Rutland <mark.rutl...@arm.com> Cc: Anna-Maria Gleixner <anna-ma...@linutronix.de> Cc: Richard Cochran <rcoch...@linutronix.de> Cc: Sebastian Andrzej Siewior <bige...@linutronix.de> Cc: Daniel Lezcano <daniel.lezc...@linaro.org> Cc: Peter Zijlstra <pet...@infradead.org>, Cc: Sebastian Frias <s...@laposte.net> Cc: Thibaud Cornic <thibaud_cor...@sigmadesigns.com> Cc: Robin Murphy <robin.mur...@arm.com> Link: http://lkml.kernel.org/r/1147ef90-7877-e4d2-bb2b-5c4fa8d31...@free.fr Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- kernel/time/tick-broadcast.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -871,6 +871,9 @@ void tick_broadcast_setup_oneshot(struct { int cpu = smp_processor_id(); + if (!bc) + return; + /* Set it up only once ! */ if (bc->event_handler != tick_handle_oneshot_broadcast) { int was_periodic = clockevent_state_periodic(bc);
