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Date:   Thu, 5 Mar 2020 10:32:06 -0800
From:   Andi Kleen <ak@linux.intel.com>
To:     Arnaldo Carvalho de Melo <acme@redhat.com>
Cc:     zhe.he@windriver.com, jolsa@kernel.org, meyerk@hpe.com,
        linux-kernel@vger.kernel.org, acme@kernel.org
Subject: Re: [PATCH] perf: Fix crash due to null pointer dereference when
 iterating cpu map
Message-ID: <20200305183206.GA1454533@tassilo.jf.intel.com>
References: <1583405239-352868-1-git-send-email-zhe.he@windriver.com>
 <20200305152755.GA6958@redhat.com>
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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.

-Andi