Re: [perf] more perf_fuzzer memory corruption

From: Vince Weaver
Date: Fri May 02 2014 - 13:42:55 EST


On Fri, 2 May 2014, Peter Zijlstra wrote:

> On Fri, May 02, 2014 at 12:43:17PM -0400, Vince Weaver wrote:
> > On Fri, 2 May 2014, Peter Zijlstra wrote:
> >
> > > In principle the vfs file refcounting should be responsible for that.
> > > But I'll go over it in a bit.
> >
> > The poll code is ancient and the C-parser in my head really can't handle
> > it very well.
>
> Yeah, that code isn't my favourite part either..
>
> > Anyway for completeness this is the kind of thing I'm seeing.
> > The poll() manpage isn't very clear about what is supposed to happen if
> > you poll() on a closed file descriptor.
>
> POLLNVAL
> Invalid request: fd not open (output only).
>
> Seems applicable..

You're right and it seems to return that properly, so having poll be
active might just be a weird co-incidence.

> Also, could you send your entire diff this way so we're more or less
> staring at the same code again?

that last test I ran was just 3.15-rc1 plus the last patch you sent,
plus a patch to allow -pg on the event.c file, plus an unrelated one that
works around the current make-kpkg debian breakage.

Vince
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