Re: [PATCH] perf evsel: fix NULL pointer deference when evsel->countsis NULL

[Colin Ian King]

On 23/01/13 22:02, Arnaldo Carvalho de Melo wrote:
> Em Mon, Jan 21, 2013 at 01:53:21PM +0900, Namhyung Kim escreveu:
> > On Sat, 19 Jan 2013 16:36:54 +0000, Colin King wrote:
> > > From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>
> > > __perf_evsel__read_on_cpu() only bails out with -ENOMEM if
> > > evsel->counts is NULL and perf_evsel__alloc_counts() has returned
> > > an error.  If perf_evsel__alloc_counts() does not return an error
> > > we get an NULL pointer deference on evsel->counts->cpu[cpu]
> > > if evsel->counts is NULL.
>
> > perf_evsel__alloc_counts() should allocate evsel->counts when it sees
> > evsel->counts is NULL and return negative error code if the allocation
> > fails.
>
> > So I don't see any problem in current code.  With your code, it won't
> > try to allocate if ->counts is NULL but overwrite existing ->counts?
>
> Right, the patch introduces a problem in code that works perfectly :-)
>
> - Arnaldo
Apologies for the noise.

Colin
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