Re: perf: perf_fuzzer triggers NULL pointer dereference

[Vince Weaver]

On Thu, 8 Nov 2018, Alexander Shishkin wrote:

> Vince Weaver <vincent.weaver@xxxxxxxxx> writes:
> 
> > 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?
> 
> scripts/decode_stacktrace.sh works most of the time.
> 
> Sounds like BTS needs fixing up again. Thanks for looking at it though!

In case it matters, it looks like the address of the oops comes down to

	linux.git/kernel/events/core.c:6393

	size += data->callchain->nr;

Vince