Re: [PATCH] fork.c: copy_process(): fix cleanup WRT perf_event_free_task()

From: Peter Zijlstra
Date: Mon Sep 29 2014 - 10:00:57 EST

On Mon, Sep 29, 2014 at 02:07:22PM +0200, Ingo Molnar wrote:
> * Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> > Subject: perf: Fix perf bug in fork()
> >
> > Oleg noticed that a cleanup by Sylvain actually uncovered a bug; by
> > calling perf_event_free_task() when failing sched_fork() we will not yet
> > have done the memset() on ->perf_event_ctxp[] and will therefore try and
> > 'free' the inherited contexts, which are still in use by the parent
> > process. This is bad..
> >
> > Suggested-by: Oleg Nesterov <oleg@xxxxxxxxxx>
> > Reported-by: Oleg Nesterov <oleg@xxxxxxxxxx>
> > Reported-by: Sylvain 'ythier' Hitier <sylvain.hitier@xxxxxxxxx>
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Could this fix a couple of fuzzer triggered perf crashes perhaps?

It could indeed I suppose.. you never know what paths those fuzzers
manage to hit.
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