mån 2018-11-19 klockan 02:02 +0100 skrev Michael Niedermayer: > On Sun, Nov 18, 2018 at 11:32:21PM +0100, Tomas Härdin wrote: > > lör 2018-11-17 klockan 03:01 +0100 skrev Michael Niedermayer: > > > Fixes: > > > 11295/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_TRUEMOTION2_fuzzer-4888953459572736 > > > > > > Found-by: continuous fuzzing process > > > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > > > > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > > > > > > --- > > > libavcodec/truemotion2.c | 6 +++--- > > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > > > diff --git a/libavcodec/truemotion2.c b/libavcodec/truemotion2.c > > > index 58a577f53c..c583ff4032 100644 > > > --- a/libavcodec/truemotion2.c > > > +++ b/libavcodec/truemotion2.c > > > @@ -484,7 +484,7 @@ static inline void tm2_high_chroma(int *data, int > > > stride, int *last, unsigned *C > > > } > > > } > > > > > > -static inline void tm2_low_chroma(int *data, int stride, int *clast, int > > > *CD, int *deltas, int bx) > > > +static inline void tm2_low_chroma(int *data, int stride, int *clast, > > > unsigned *CD, int *deltas, int bx) > > > { > > > int t; > > > int l; > > > @@ -494,8 +494,8 @@ static inline void tm2_low_chroma(int *data, int > > > stride, int *clast, int *CD, in > > > prev = clast[-3]; > > > else > > > prev = 0; > > > - t = (CD[0] + CD[1]) >> 1; > > > - l = (prev - CD[0] - CD[1] + clast[1]) >> 1; > > > + t = (int)(CD[0] + CD[1]) >> 1; > > > > I presume the old code would overflow for sums exceeding INT_MAX. > > There were overflows in the sense of undefined behavior, yes > > > > Why > > then is there a cast to int before the shift and not after? > > because shifts of signed and unsigned values produce different results > > maybe the unsigned type confused you. CD is signed in a semantic sense its > stored in a unsigned type because otherwise this code has undefined behavior. > It would be better to use a type with different name but that had lead to > long arguments that went nowhere in the past. So i tend to use plain > unsigned now for these kind of cases as it seems that is what most people > prefer.
So signed overflow is intended? Huh, weird format. /Tomas _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
