[FFmpeg-devel] [PATCH] lavfi/mptestsrc: fix invalid access in case of negative linesize

[Paul B Mahol]

On 4/18/13, Stefano Sabatini <stefasab at gmail.com> wrote:
> On date Wednesday 2013-04-17 22:12:06 +0200, Stefano Sabatini encoded:
>> In particular, fix crash with:
>> ffplay -f lavfi mptestsrc,vflip
>> ---
>>  libavfilter/vsrc_mptestsrc.c |   12 ++++++++----
>>  1 file changed, 8 insertions(+), 4 deletions(-)
>>
>> diff --git a/libavfilter/vsrc_mptestsrc.c b/libavfilter/vsrc_mptestsrc.c
>> index 867cd50..e931c76 100644
>> --- a/libavfilter/vsrc_mptestsrc.c
>> +++ b/libavfilter/vsrc_mptestsrc.c
>> @@ -301,9 +301,10 @@ static int request_frame(AVFilterLink *outlink)
>>  {
>>      MPTestContext *test = outlink->src->priv;
>>      AVFrame *picref;
>> -    int w = WIDTH, h = HEIGHT, ch = h>>test->vsub;
>> +    int w = WIDTH, h = HEIGHT, cw = w>>test->hsub, ch = h>>test->vsub;
>>      unsigned int frame = test->frame_nb;
>>      enum test_type tt = test->test;
>> +    int i;
>>
>>      if (test->max_pts >= 0 && test->pts > test->max_pts)
>>          return AVERROR_EOF;
>> @@ -313,9 +314,12 @@ static int request_frame(AVFilterLink *outlink)
>>      picref->pts = test->pts++;
>>
>>      // clean image
>> -    memset(picref->data[0], 0,   picref->linesize[0] * h);
>> -    memset(picref->data[1], 128, picref->linesize[1] * ch);
>> -    memset(picref->data[2], 128, picref->linesize[2] * ch);
>> +    for (i = 0; i < h; i++)
>> +        memset(picref->data[0] + i*picref->linesize[0], 0, w);
>> +    for (i = 0; i < ch; i++) {
>> +        memset(picref->data[1] + i*picref->linesize[1], 128, cw);
>> +        memset(picref->data[2] + i*picref->linesize[2], 128, cw);
>> +    }
>
> Ping, will push tomorrow if I see no comments.


It should be fine, but adding helpers (like av_copy_plane) would not hurt.

> --
> FFmpeg = Friendly & Fierce Mystic Portentous Ermetic Gangster
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>