path: root/arch
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authorSebastian Andrzej Siewior <bigeasy@linutronix.de>2016-09-20 15:12:21 +0200
committerThomas Gleixner <tglx@linutronix.de>2016-09-20 16:06:09 +0200
commitf1e1c9e5e357c05253affb13be29285c5cb56bf0 (patch)
tree941b58db15a63e880950eb986590564e181f0217 /arch
parent3be7988674ab33565700a37b210f502563d932e6 (diff)
perf/x86/intel/bts: Make sure debug store is valid
Since commit 4d4c47412464 ("perf/x86/intel/bts: Fix BTS PMI detection") my box goes boom on boot: | .... node #0, CPUs: #1 #2 #3 #4 #5 #6 #7 | BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 | IP: [<ffffffff8100c463>] intel_bts_interrupt+0x43/0x130 | Call Trace: | <NMI> d [<ffffffff8100b341>] intel_pmu_handle_irq+0x51/0x4b0 | [<ffffffff81004d47>] perf_event_nmi_handler+0x27/0x40 This happens because the code introduced in this commit dereferences the debug store pointer unconditionally. The debug store is not guaranteed to be available, so a NULL pointer check as on other places is required. Fixes: 4d4c47412464 ("perf/x86/intel/bts: Fix BTS PMI detection") Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: vince@deater.net Cc: eranian@google.com Link: http://lkml.kernel.org/r/20160920131220.xg5pbdjtznszuyzb@breakpoint.cc Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch')
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c
index bdcd6510992c..6ff66efa0feb 100644
--- a/arch/x86/events/intel/bts.c
+++ b/arch/x86/events/intel/bts.c
@@ -455,7 +455,7 @@ int intel_bts_interrupt(void)
* The only surefire way of knowing if this NMI is ours is by checking
* the write ptr against the PMI threshold.
- if (ds->bts_index >= ds->bts_interrupt_threshold)
+ if (ds && (ds->bts_index >= ds->bts_interrupt_threshold))
handled = 1;