Patch "tick/broadcast: Prevent NULL pointer dereference" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

tick/broadcast: Prevent NULL pointer dereference

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
tick-broadcast-prevent-null-pointer-dereference.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Thomas Gleixner <[email protected]>
Date: Thu, 15 Dec 2016 12:10:37 +0100
Subject: tick/broadcast: Prevent NULL pointer dereference

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.

---
 kernel/time/tick-broadcast.c |    3 +++
 1 file changed, 3 insertions(+)

@@ -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);

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/clocksource-dummy_timer-move-hotplug-callback-after-the-real-timers.patch queue-4.9/irqchip-bcm7038-l1-implement-irq_cpu_offline-callback.patch queue-4.9/x86-cpu-probe-cpuid-leaf-6-even-when-cpuid_level-6.patch queue-4.9/x86-prctl-uapi-remove-ifdef-for-checkpoint_restore.patch queue-4.9/efi-efivar_ssdt_load-don-t-return-success-on-allocation-failure.patch queue-4.9/pci-msi-check-for-null-affinity-mask-in-pci_irq_get_affinity.patch queue-4.9/genirq-affinity-fix-node-generation-from-cpumask.patch queue-4.9/tick-broadcast-prevent-null-pointer-dereference.patch