linux-kernel - Re: perf: perf_fuzzer triggers vmalloc

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Date:   Mon, 24 Oct 2016 13:16:35 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Vince Weaver <vincent.weaver@...ne.edu>,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Andy Lutomirski <luto@...nel.org>
Subject: Re: perf: perf_fuzzer triggers vmalloc_fault (then crashes)

On Mon, Oct 24, 2016 at 06:14:02AM -0500, Josh Poimboeuf wrote:

> > Josh, Andy, any clue on how I should go about fixing this?
> 
> This is a bug in the unwinder.  The NMI hit in the entry code right
> after setting up the stack pointer from cpu_current_top_of_stack, so the
> kernel stack was empty.  __unwind_start() tried to dereference the
> pointer (0xffffc90008500000) at the top of the stack.  I'll make a
> patch.

Great, thanks!