| Message ID | 20190711214940.13431-1-michael@niedermayer.cc |
|---|---|
| State | New |
| Headers | show |
On 7/11/2019 6:49 PM, Michael Niedermayer wrote: > Fixes: left shift of negative value -456 > Fixes: 15561/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPC8_fuzzer-5758130404720640 > > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> > --- > libavcodec/mpc8.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/libavcodec/mpc8.c b/libavcodec/mpc8.c > index 3be2f79a5a..75943064da 100644 > --- a/libavcodec/mpc8.c > +++ b/libavcodec/mpc8.c > @@ -364,7 +364,7 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data, > for(j = 0; j < SAMPLES_PER_BAND; j += SAMPLES_PER_BAND / 2){ > cnt = get_vlc2(gb, q1_vlc.table, MPC8_Q1_BITS, 2); > t = mpc8_get_mask(gb, 18, cnt); > - for(k = 0; k < SAMPLES_PER_BAND / 2; k++, t <<= 1) > + for(k = 0; k < SAMPLES_PER_BAND / 2; k++, t += (unsigned)t) How about something like this instead (Untested) for(k = 0; k < SAMPLES_PER_BAND / 2; k++) c->Q[ch][off + j + k] = t & (1 << (SAMPLES_PER_BAND / 2 - k - 1)) ? (get_bits1(gb) << 1) - 1 : 0; > c->Q[ch][off + j + k] = (t & 0x20000) ? (get_bits1(gb) << 1) - 1 : 0; > } > break; >
On Thu, Jul 11, 2019 at 07:37:15PM -0300, James Almer wrote: > On 7/11/2019 6:49 PM, Michael Niedermayer wrote: > > Fixes: left shift of negative value -456 > > Fixes: 15561/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPC8_fuzzer-5758130404720640 > > > > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> > > --- > > libavcodec/mpc8.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/libavcodec/mpc8.c b/libavcodec/mpc8.c > > index 3be2f79a5a..75943064da 100644 > > --- a/libavcodec/mpc8.c > > +++ b/libavcodec/mpc8.c > > @@ -364,7 +364,7 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data, > > for(j = 0; j < SAMPLES_PER_BAND; j += SAMPLES_PER_BAND / 2){ > > cnt = get_vlc2(gb, q1_vlc.table, MPC8_Q1_BITS, 2); > > t = mpc8_get_mask(gb, 18, cnt); > > - for(k = 0; k < SAMPLES_PER_BAND / 2; k++, t <<= 1) > > + for(k = 0; k < SAMPLES_PER_BAND / 2; k++, t += (unsigned)t) > > How about something like this instead (Untested) > > for(k = 0; k < SAMPLES_PER_BAND / 2; k++) > c->Q[ch][off + j + k] = t & (1 << (SAMPLES_PER_BAND / 2 - k - 1)) > ? (get_bits1(gb) << 1) - 1 : 0; tested, works, will apply with this Thanks [...]
diff --git a/libavcodec/mpc8.c b/libavcodec/mpc8.c index 3be2f79a5a..75943064da 100644 --- a/libavcodec/mpc8.c +++ b/libavcodec/mpc8.c @@ -364,7 +364,7 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data, for(j = 0; j < SAMPLES_PER_BAND; j += SAMPLES_PER_BAND / 2){ cnt = get_vlc2(gb, q1_vlc.table, MPC8_Q1_BITS, 2); t = mpc8_get_mask(gb, 18, cnt); - for(k = 0; k < SAMPLES_PER_BAND / 2; k++, t <<= 1) + for(k = 0; k < SAMPLES_PER_BAND / 2; k++, t += (unsigned)t) c->Q[ch][off + j + k] = (t & 0x20000) ? (get_bits1(gb) << 1) - 1 : 0; } break;
Fixes: left shift of negative value -456 Fixes: 15561/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPC8_fuzzer-5758130404720640 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> --- libavcodec/mpc8.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)