From: Peter Zijlstra <peterz@infradead.org>
To: Vince Weaver <vincent.weaver@maine.edu>
Cc: linux-kernel@vger.kernel.org,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Jiri Olsa <jolsa@redhat.com>, Ingo Molnar <mingo@redhat.com>,
Paul Mackerras <paulus@samba.org>,
Stephane Eranian <eranian@google.com>
Subject: Re: perf: fuzzer triggers NULL pointer derefreence in x86_schedule_events
Date: Fri, 1 May 2015 14:59:55 +0200 [thread overview]
Message-ID: <20150501125955.GF5029@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <alpine.DEB.2.11.1504301448440.30050@vincent-weaver-1.umelst.maine.edu>
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.
next prev parent reply other threads:[~2015-05-01 13:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-30 19:08 perf: fuzzer triggers NULL pointer derefreence in x86_schedule_events Vince Weaver
2015-05-01 12:59 ` Peter Zijlstra [this message]
2015-05-04 19:32 ` Stephane Eranian
2015-05-07 12:43 ` Peter Zijlstra
2015-05-08 4:25 ` Vince Weaver
2015-05-18 17:40 ` Vince Weaver
2015-05-20 13:03 ` Peter Zijlstra
2015-05-20 13:15 ` Peter Zijlstra
2015-05-20 13:49 ` Peter Zijlstra
2015-05-20 15:26 ` Peter Zijlstra
2015-05-20 16:09 ` Peter Zijlstra
2015-05-24 19:14 ` Jiri Olsa
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