Messages in this thread | | | Date | Wed, 7 May 2014 12:46:24 -0400 (EDT) | From | Vince Weaver <> | Subject | Re: perf_fuzzer crash on pentium 4 |
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On Wed, 7 May 2014, Cyrill Gorcunov wrote:
> On Tue, May 06, 2014 at 05:30:19PM -0400, Vince Weaver wrote: > > On Wed, 7 May 2014, Cyrill Gorcunov wrote: > > > > > > [ 67.872274] BUG: unable to handle kernel NULL pointer dereference at 00000004 > > > > [ 67.876146] IP: [<ffffffff81013df2>] p4_pmu_schedule_events+0xa5/0x331 > > > > > > This looks like > > > > > > p4_pmu_schedule_events: > > > ... > > > bind = p4_config_get_bind(hwc->config); > > > returned bind = NULL; > > > escr_idx = p4_get_escr_idx(bind->escr_msr[thread]); NULL deref > > > > > > If i'm right (btw it's possible to use addr2line helper?) > > > > Yes, the address maps to > > > > escr_idx = p4_get_escr_idx(bind->escr_msr[thread]); > > Great, now we knows the reason of the issue, only to figure out > why is left ;) > > > > then hwc->config > > > is corrupted and p4_config_get_bind returned nil simply because proper event > > > was not found. And I don't understand how it could happen because before > > > configuration gets written into hwc->config it's validated once obtained > > > from user-space as a raw event. Weird... > > > > I'll try to get some sort of trace out if it to see what event is being > > tried. > > Yeah, this would help a lot.
sorry for the delay, I like to compile kernels locally and it takes a really long time to build a ftrace-enabled kernel on a pentium 4 it seems.
Anyway I threw some printks in, and this is what I get:
[ 447.572626] VMW: bind=NULL config=6b6b6b6b6b6b6b6b
I have slab poisoning turned on. Use after free?
Vince
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