[FFmpeg-devel] [PATCH] avcodec/vp3: Check that there will be sufficient input for the coded fragments in unpack_superblocks()

Paul B Mahol onemda at gmail.com
Sun May 6 12:52:50 EEST 2018


On 5/6/18, Michael Niedermayer <michael at niedermayer.cc> wrote:
> On Sat, May 05, 2018 at 09:14:52PM +0200, wm4 wrote:
>> On Sat,  5 May 2018 21:10:06 +0200
>> Michael Niedermayer <michael at niedermayer.cc> wrote:
>>
>> > Fixes: Timeout
>> > Fixes:
>> > 6292/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VP3_fuzzer-4871218218926080
>> >
>> > Found-by: continuous fuzzing process
>> > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
>> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
>> > ---
>> >  libavcodec/vp3.c | 6 +++++-
>> >  1 file changed, 5 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/libavcodec/vp3.c b/libavcodec/vp3.c
>> > index 1d83753314..fcc19a627b 100644
>> > --- a/libavcodec/vp3.c
>> > +++ b/libavcodec/vp3.c
>> > @@ -543,7 +543,11 @@ static int unpack_superblocks(Vp3DecodeContext *s,
>> > GetBitContext *gb)
>> >                                           : s->y_superblock_count);
>> >          int num_coded_frags = 0;
>> >
>> > -        for (i = sb_start; i < sb_end && get_bits_left(gb) > 0; i++) {
>> > +        for (i = sb_start; i < sb_end; i++) {
>> > +            if (get_bits_left(gb) < ((s->total_num_coded_frags +
>> > num_coded_frags) >> 2)) {
>> > +                av_log(s->avctx, AV_LOG_ERROR, "Insufficient input data
>> > for coded fragments\n");
>> > +                return AVERROR_INVALIDDATA;
>> > +            }
>> >              /* iterate through all 16 fragments in a superblock */
>> >              for (j = 0; j < 16; j++) {
>> >                  /* if the fragment is in bounds, check its coding
>> > status */
>>
>> The log message is pointless bloat.
>
> All error returns of this function print a log message.

Please remove log function, it is not needed at all.


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