On Tue, 15 Apr 2014, Vince Weaver wrote:
>
> Still tracking memory corruption bugs found by the perf_fuzzer, I have
> about 10 different log splats that I think might all be related to the
> same underlying problem.
>
> Anyway I managed to trigger this using the perf_fuzzer:
>
> [ 221.065278] Slab corruption (Not tainted): kmalloc-2048
> start=ffff8800cd15e800, len=2048
> [ 221.074062] 040: 6b 6b 6b 6b 6b 6b 6b 6b 98 72 57 cd 00 88 ff ff
> kkkkkkkk.rW.....
> [ 221.082321] Prev obj: start=ffff8800cd15e000, len=2048
> [ 221.087933] 000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> [ 221.096224] 010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
>
> And luckily I had ftrace running at the time.
>
> The allocation of this block is by perf_event
>
> perf_fuzzer-2520 [001] 182.980563: kmalloc:
> (perf_event_alloc+0x55) call_site=ffffffff811399b5 ptr=0xffff8800cd15e800
> bytes_req=1272 bytes_alloc=2048 gfp_flags=GFP_KERNEL|GFP_ZERO
> perf_fuzzer-2520 [000] 183.628515: kmalloc:
> (perf_event_alloc+0x55) call_site=ffffffff811399b5 ptr=0xffff8800cd15e800
> bytes_req=1272 bytes_alloc=2048 gfp_flags=GFP_KERNEL|GFP_ZERO
> perf_fuzzer-2520 [000] 183.628521: kfree:
> (perf_event_alloc+0x2f7) call_site=ffffffff81139c57 ptr=0xffff8800cd15e800
> perf_fuzzer-2520 [000] 183.628844: kmalloc:
> (perf_event_alloc+0x55) call_site=ffffffff811399b5 ptr=0xffff8800cd15e800
> bytes_req=1272 bytes_alloc=2048 gfp_flags=GFP_KERNEL|GFP_ZERO
> ...(thousands of times of kmalloc/kfree)
>
> Is it worth wading through this mess to try to track down what happened?
Definitely worth a try. Can you upload the trace file and provide the
URL or send it offlist in private mail if you cannot provide a public URL.
Thanks,
tglx
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