Patch "cpu/hotplug: Keep enough storage space if SMP=n to avoid array out of bounds scribble" has been added to the 4.6-stable tree

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

cpu/hotplug: Keep enough storage space if SMP=n to avoid array out of bounds scribble

to the 4.6-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:
cpu-hotplug-keep-enough-storage-space-if-smp-n-to-avoid-array-out-of-bounds-scribble.patch
and it can be found in the queue-4.6 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: Tue, 12 Jul 2016 21:59:23 +0200
Subject: cpu/hotplug: Keep enough storage space if SMP=n to avoid array out of bounds scribble

From: Thomas Gleixner <[email protected]>

commit a7c734140aa36413944eef0f8c660e0e2256357d upstream.

Xiaolong Ye reported lock debug warnings triggered by the following commit:

8de4a0066106 ("perf/x86: Convert the core to the hotplug state machine")

The bug is the following: the cpuhp_bp_states[] array is cut short when CONFIG_SMP=n, but the dynamically registered callbacks are stored nevertheless and happily scribble outside of the array bounds...

We need to store them in case that the state is unregistered so we can invoke the teardown function. That's independent of CONFIG_SMP. Make sure the array is large enough.

---
 kernel/cpu.c |    2 ++
 1 file changed, 2 insertions(+)

@@ -1218,6 +1218,8 @@ static struct cpuhp_step cpuhp_bp_states
 		.teardown		= takedown_cpu,
 		.cant_stop		= true,
 	},
+#else
+	[CPUHP_BRINGUP_CPU] = { },
 #endif
 };
 

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

queue-4.6/cpu-hotplug-keep-enough-storage-space-if-smp-n-to-avoid-array-out-of-bounds-scribble.patch queue-4.6/x86-quirks-apply-nvidia_bugs-quirk-only-on-root-bus.patch queue-4.6/irqchip-mips-gic-match-ipi-irq-domain-by-bus-token-only.patch queue-4.6/x86-quirks-add-early-quirk-to-reset-apple-airport-card.patch queue-4.6/sched-fair-fix-effective_load-to-consistently-use-smoothed-load.patch queue-4.6/sched-debug-fix-deadlock-when-enabling-sched-events.patch queue-4.6/x86-quirks-reintroduce-scanning-of-secondary-buses.patch queue-4.6/irqchip-mips-gic-map-to-vps-using-hw-vpnum.patch queue-4.6/kernel-sysrq-watchdog-sched-core-reset-watchdog-on-all-cpus-while-processing-sysrq-w.patch queue-4.6/posix_cpu_timer-exit-early-when-process-has-been-reaped.patch