linux-kernel - Re: perf: perf_fuzzer triggers NULL pointer dereference

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Message-ID: <alpine.DEB.2.21.1811081100490.7406@macbook-air>
Date:   Thu, 8 Nov 2018 11:05:07 -0500 (EST)
From:   Vince Weaver <vincent.weaver@...ne.edu>
To:     Vince Weaver <vincent.weaver@...ne.edu>
cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        torvalds@...ux-foundation.org
Subject: Re: perf: perf_fuzzer triggers NULL pointer dereference

On Thu, 8 Nov 2018, Vince Weaver wrote:

> [91760.326510] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
> [91760.334876] PGD 0 P4D 0 
> [91760.337596] Oops: 0000 [#1] SMP PTI
> [91760.341332] CPU: 6 PID: 0 Comm: swapper/6 Tainted: G        W         4.20.0-rc1+ #119
> [91760.349816] Hardware name: LENOVO 10AM000AUS/SHARKBAY, BIOS FBKT72AUS 01/26/2014
> [91760.357723] RIP: 0010:perf_prepare_sample+0x82/0x4a0

so what's the best way to do the equivelent of addr2line on something like 
this, now that we aren't allowed to know the RIP anymore?

I probably knew at one point but I've spent the last 3 months doing 6502 
assembly language Demoscene coding and so apparently I've forgotten 
everything I once knew about x86_64 kernel interfaces.  (As can be 
imagined, Demoscene coding work is a lot more mentally rewarding than 
perf_fuzzer work).

Vince