Messages in this thread | | | Date | Wed, 20 May 2015 15:15:25 +0200 | From | Peter Zijlstra <> | Subject | Re: perf: fuzzer triggers NULL pointer derefreence in x86_schedule_events |
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On Wed, May 20, 2015 at 03:03:12PM +0200, Peter Zijlstra wrote: > So new in this release is: > > static void intel_put_event_constraints(struct cpu_hw_events *cpuc, > struct perf_event *event) > { > ... > > /* cleanup dynamic constraint */ > if (c && (c->flags & PERF_X86_EVENT_DYNAMIC)) > event->hw.constraint = NULL; > } > > Which is the only place that value is ever cleared... > > Now, I've not quite figured out how that can intersect with scheduling, > typically we only call put_event_constraints() when we're done with the > event.
Related to that; intel_commit_scheduling() has:
c = event->hw.constraint;
if (!c) return;
Stephane, how can that ever be?
x86_schedule_events() does: hwc->constraint = get_event_constraints()
for all events, and intel_get_event_constraints() will _always_ return a valid constraint -- &unconstrained if nothing else.
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