Messages in this thread | | | Date | Fri, 1 May 2015 14:59:55 +0200 | From | Peter Zijlstra <> | Subject | Re: perf: fuzzer triggers NULL pointer derefreence in x86_schedule_events |
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On Thu, Apr 30, 2015 at 03:08:56PM -0400, Vince Weaver wrote: > > So the perf_fuzzer caught this after about a week of fuzzing on a Haswell > machine running a recent git kernel (pre 4.1-rc1 though). > > We've seen this BUG before and various fixes were applied but apparently > it wasn't enough. > > Sadly it doesn't seem to be reproducible. > > validate_group() -> x86_pmu.schedule_events() -> ???? -> variable_test_bit() > (hard to tell which test bit with all the inlining going on).
Assuming you build with debug info addr2line -i can help, but I think I found it by comparing the Code section below with my objdump -D output.
Its: /* constraint still honored */ if (!test_bit(hwc->idx, c->idxmsk)) break;
Which would seem to suggest c is NULL.
Lemme go figure out how that could happen.
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