| From | Willy Tarreau <> | Subject | [PATCH 3.10 083/268] tick/broadcast: Prevent NULL pointer dereference | Date | Mon, 19 Jun 2017 20:29:42 +0200 |
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From: Thomas Gleixner <tglx@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.tmp@free.fr> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Anna-Maria Gleixner <anna-maria@linutronix.de> Cc: Richard Cochran <rcochran@linutronix.de> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org>, Cc: Sebastian Frias <sf84@laposte.net> Cc: Thibaud Cornic <thibaud_cornic@sigmadesigns.com> Cc: Robin Murphy <robin.murphy@arm.com> Link: http://lkml.kernel.org/r/1147ef90-7877-e4d2-bb2b-5c4fa8d3144b@free.fr Signed-off-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Willy Tarreau <w@1wt.eu> --- kernel/time/tick-broadcast.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 19ee339..6f27814 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -775,6 +775,9 @@ void tick_broadcast_setup_oneshot(struct clock_event_device *bc) { int cpu = smp_processor_id(); + if (!bc) + return; + /* Set it up only once ! */ if (bc->event_handler != tick_handle_oneshot_broadcast) { int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC; -- 2.8.0.rc2.1.gbe9624a
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