4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Thomas Gleixner <[email protected]> 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 <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Cc: Mark Rutland <[email protected]> Cc: Anna-Maria Gleixner <[email protected]> Cc: Richard Cochran <[email protected]> Cc: Sebastian Andrzej Siewior <[email protected]> Cc: Daniel Lezcano <[email protected]> Cc: Peter Zijlstra <[email protected]>, Cc: Sebastian Frias <[email protected]> Cc: Thibaud Cornic <[email protected]> Cc: Robin Murphy <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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);
