[FFmpeg-devel] [PATCH 2/2] webmdashenc: Fix potential leak in realloc

[Vignesh Venkatasubramanian]

On Tue, Apr 14, 2015 at 3:38 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Mon, Apr 13, 2015 at 01:58:30PM -0700, Vignesh Venkatasubramanian wrote:
>> On Mon, Apr 13, 2015 at 12:48 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> > On Mon, Apr 13, 2015 at 12:16:44PM -0700, Vignesh Venkatasubramanian wrote:
>> >> Fix potential leak in av_realloc call where the output was being
>> >> overwritten by using a temporary variable.
>> >>
>> >> Signed-off-by: Vignesh Venkatasubramanian <vigneshv at google.com>
>> >> ---
>> >>  libavformat/webmdashenc.c | 5 +++--
>> >>  1 file changed, 3 insertions(+), 2 deletions(-)
>> >>
>> >> diff --git a/libavformat/webmdashenc.c b/libavformat/webmdashenc.c
>> >> index 80266f7..0f915fd 100644
>> >> --- a/libavformat/webmdashenc.c
>> >> +++ b/libavformat/webmdashenc.c
>> >> @@ -419,9 +419,10 @@ static int parse_adaptation_sets(AVFormatContext *s)
>> >>          if (*p == ' ')
>> >>              continue;
>> >>          else if (state == new_set && !strncmp(p, "id=", 3)) {
>> >> -            w->as = av_realloc(w->as, sizeof(*w->as) * ++w->nb_as);
>> >> -            if (w->as == NULL)
>> >> +            void *mem = av_realloc(w->as, sizeof(*w->as) * ++w->nb_as);
>> >> +            if (mem == NULL)
>> >>                  return AVERROR(ENOMEM);
>> >
>> > nb_as will be 1 larger than the array in the return case
>> > is that intended / safe ?
>> >
>>
>> yes, that value shouldn't be used anywhere else. anyway, i'm reworking
>> a lot of error handling in this file. so this is fine for now.
>
> nb_as is used in webm_dash_manifest_write_trailer() too
>

right. i'll upload a follow up patch that addresses those cases.

> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> It is what and why we do it that matters, not just one of them.
>
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-- 
Vignesh