lavf: avoid integer overflow in ff_compute_frame_duration()

Scaling the denominator instead of the numerator if it is too large
loses precision. Fixes an assert caused by a negative frame duration in
the fuzzed sample nasa-8s2.ts_s202310.

CC: libav-stable@libav.org
This commit is contained in:
Janne Grunau 2012-11-23 14:05:36 +01:00
parent 5ae72f5453
commit 7709ce029a
1 changed files with 4 additions and 1 deletions

View File

@ -725,7 +725,10 @@ void ff_compute_frame_duration(int *pnum, int *pden, AVStream *st,
*pnum = st->codec->time_base.num;
*pden = st->codec->time_base.den;
if (pc && pc->repeat_pict) {
*pnum = (*pnum) * (1 + pc->repeat_pict);
if (*pnum > INT_MAX / (1 + pc->repeat_pict))
*pden /= 1 + pc->repeat_pict;
else
*pnum *= 1 + pc->repeat_pict;
}
//If this codec can be interlaced or progressive then we need a parser to compute duration of a packet
//Thus if we have no parser in such case leave duration undefined.