Messages in this thread | | | Date | Fri, 6 Mar 2020 09:30:00 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH] perf: Fix crash due to null pointer dereference when iterating cpu map |
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On Fri, Mar 06, 2020 at 03:20:55PM +0800, He Zhe wrote: > > > On 3/6/20 3:58 AM, Arnaldo Carvalho de Melo wrote: > > Em Thu, Mar 05, 2020 at 10:32:06AM -0800, Andi Kleen escreveu: > >> On Thu, Mar 05, 2020 at 12:27:55PM -0300, Arnaldo Carvalho de Melo wrote: > >>> Em Thu, Mar 05, 2020 at 06:47:19PM +0800, zhe.he@windriver.com escreveu: > >>>> From: He Zhe <zhe.he@windriver.com> > >>>> > >>>> NULL pointer may be passed to perf_cpu_map__cpu and then cause the > >>>> following crash. > >>>> > >>>> perf ftrace -G start_kernel ls > >>>> failed to set tracing filters > >>>> [ 208.710716] perf[341]: segfault at 4 ip 00000000567c7c98 > >>>> sp 00000000ff937ae0 error 4 in perf[56630000+1b2000] > >>>> [ 208.724778] Code: fc ff ff e8 aa 9b 01 00 8d b4 26 00 00 00 00 8d > >>>> 76 00 55 89 e5 83 ec 18 65 8b 0d 14 00 00 00 89 > >>>> 4d f4 31 c9 8b 45 08 8b9 > >>>> Segmentation fault > >>> I'm not being able to repro this here, what is the tree you are using? > >> I believe that's the same bug that Jann Horn reported recently for perf trace. > >> I thought the patch for that went in. > > Ok, Zhe, that patch is at the end of this message, and it is in: > > > > [acme@five perf]$ git tag --contains cb71f7d43ece3d5a4f400f510c61b2ec7c9ce9a1 | grep ^v > > v5.6-rc1 > > v5.6-rc2 > > v5.6-rc3 > > v5.6-rc4 > > [acme@five perf]$ > > > > Can you try with that? > > Thanks, that does fix the issue I met. > > BTW, my change in perf_cpu_map__cpu can be used as a preventive check > and the "1" in perf_cpu_map__cpu should be "0", and assigning a NULL in
I agree, can't see why we had 1 in here.. must be connected to the dummy map.. could you please double check with all the perf_cpu_map__nr usages that the 0 will work as expected?
> perf_evlist__exit makes the clearing complete. So are they worth a new patch?
the rest of the hunks looks good as preventive checks
thanks, jirka
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