| Message ID | 20190109000122.17610-1-michael@niedermayer.cc |
|---|---|
| State | Accepted |
| Headers | show |
2019-01-09 1:01 GMT+01:00, Michael Niedermayer <michael@niedermayer.cc>:
> + for (i= 1; i<buf_size; i+=2) {
This looks too inconsistent.
Carl Eugen
On Wed, Jan 09, 2019 at 09:40:05PM +0100, Carl Eugen Hoyos wrote: > 2019-01-09 1:01 GMT+01:00, Michael Niedermayer <michael@niedermayer.cc>: > > > + for (i= 1; i<buf_size; i+=2) { > > This looks too inconsistent. locally done: - for (i= 1; i<buf_size; i+=2) { + for (i = 1; i < buf_size; i += 2) { thanks [...]
On Thu, Jan 10, 2019 at 01:37:07AM +0100, Michael Niedermayer wrote: > On Wed, Jan 09, 2019 at 09:40:05PM +0100, Carl Eugen Hoyos wrote: > > 2019-01-09 1:01 GMT+01:00, Michael Niedermayer <michael@niedermayer.cc>: > > > > > + for (i= 1; i<buf_size; i+=2) { > > > > This looks too inconsistent. > > locally done: > > - for (i= 1; i<buf_size; i+=2) { > + for (i = 1; i < buf_size; i += 2) { will apply with this change thx [...]
diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c index ba731314b4..1e89ba9ce2 100644 --- a/libavcodec/ac3dec.c +++ b/libavcodec/ac3dec.c @@ -1467,6 +1467,7 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data, int buf_size, full_buf_size = avpkt->size; AC3DecodeContext *s = avctx->priv_data; int blk, ch, err, offset, ret; + int i; int skip = 0, got_independent_frame = 0; const uint8_t *channel_map; uint8_t extended_channel_map[EAC3_MAX_CHANNELS]; @@ -1477,14 +1478,21 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data, s->superframe_size = 0; buf_size = full_buf_size; - while (buf_size > 2) { - if (AV_RB16(buf) != 0x770B && AV_RL16(buf) != 0x770B) { - buf += 1; - buf_size -= 1; - continue; + for (i= 1; i<buf_size; i+=2) { + if (buf[i] == 0x77 || buf[i] == 0x0B) { + if ((buf[i] ^ buf[i-1]) == (0x77 ^ 0x0B)) { + i--; + break; + } else if ((buf[i] ^ buf[i+1]) == (0x77 ^ 0x0B)) { + break; + } } - break; } + if (i >= buf_size) + return AVERROR_INVALIDDATA; + buf += i; + buf_size -= i; + /* copy input buffer to decoder context to avoid reading past the end of the buffer, which can be caused by a damaged input stream. */ if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
Fixes: Timeout Fixes: 11619/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AC3_FIXED_fuzzer-5632398021099520 Fixes: 11620/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AC3_fuzzer-5711996515778560 Fixes: 11658/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_EAC3_fuzzer-5701006524940288 Before: Executed clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AC3_FIXED_fuzzer-5632398021099520 in 20338 ms After: Executed clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AC3_FIXED_fuzzer-5632398021099520 in 11825 ms Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> --- libavcodec/ac3dec.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-)