On Sat, Aug 19, 2017 at 04:00:18PM +0200, Paul B Mahol wrote: > On 8/19/17, Michael Niedermayer <mich...@niedermayer.cc> wrote: > > On Fri, Aug 18, 2017 at 06:21:56PM +0200, Paul B Mahol wrote: > >> On 8/18/17, Michael Niedermayer <mich...@niedermayer.cc> wrote: > >> > Fixes: runtime error: shift exponent 4294967289 is too large for 32-bit > >> > type > >> > 'int' > >> > Fixes: 3030/clusterfuzz-testcase-minimized-4649809254285312 > >> > > >> > Found-by: continuous fuzzing process > >> > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > >> > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > >> > --- > >> > libavcodec/pixlet.c | 2 +- > >> > 1 file changed, 1 insertion(+), 1 deletion(-) > >> > > >> > diff --git a/libavcodec/pixlet.c b/libavcodec/pixlet.c > >> > index 088226bdda..a9cfe085c9 100644 > >> > --- a/libavcodec/pixlet.c > >> > +++ b/libavcodec/pixlet.c > >> > @@ -262,7 +262,7 @@ static int read_high_coeffs(AVCodecContext *avctx, > >> > uint8_t *src, int16_t *dst, i > >> > > >> > flag = 0; > >> > > >> > - if (state * 4ULL > 0xFF || i >= size) > >> > + if ((uint64_t)state > 0xFF / 4 || i >= size) > >> > >> This is not exact same behaviour. > > > > no, it differs for a small number of cases that have one of the 2 > > most significant bits (of the 64 bits) set in state. > > I think this was a bug i introduced in a previous commit. > > > > If above change is not the correct thing to do, please elaborate. > > state is passed into ff_clz() later which has no deterministic > > behavior when these MSBs are set as ff_clz() uses unsigned and state > > is int64_t and unsigned can be 32 or 64bit. > > Only 32 bits matters for ff_clz() anyway.
your reply is a bit terse. Does that mean you have no objections to the patch ? about ff_clz(), with 64bit unsigned a ff_clz(1) should return 63, the code looks like it expects 31 [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB If you fake or manipulate statistics in a paper in physics you will never get a job again. If you fake or manipulate statistics in a paper in medicin you will get a job for life at the pharma industry.
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