On Thu, Apr 04, 2024 at 07:12:40PM +0200, Marton Balint wrote: > > > On Thu, 4 Apr 2024, Michael Niedermayer wrote: > > > Fixes: signed integer overflow: 65792 * 65312 cannot be represented in type > > 'int' > > Fixes: > > 67819/clusterfuzz-testcase-minimized-ffmpeg_dem_WADY_fuzzer-5236100912185344 > > > > Found-by: continuous fuzzing process > > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > > --- > > libavformat/pcm.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/libavformat/pcm.c b/libavformat/pcm.c > > index 051e86dd464..a774dbc3726 100644 > > --- a/libavformat/pcm.c > > +++ b/libavformat/pcm.c > > @@ -41,7 +41,7 @@ int ff_pcm_default_packet_size(AVCodecParameters *par) > > /* Don't trust the codecpar bitrate if we can calculate it ourselves */ > > if (bits_per_sample > 0 && par->sample_rate > 0 && > > par->ch_layout.nb_channels > 0) > > if ((int64_t)par->sample_rate * par->ch_layout.nb_channels < > > INT64_MAX / bits_per_sample) > > - bitrate = bits_per_sample * par->sample_rate * > > par->ch_layout.nb_channels; > > + bitrate = bits_per_sample * (int64_t)par->sample_rate * > > par->ch_layout.nb_channels; > > LGTM, thanks. > > I wonder why we usually cast the second operand and not the first to 64 bit, > since cast has higher precedence than multiplication, it should not matter, > should it?
If the reader isnt sure about the precedence, writing it as a * (int64_t)b has the advantage that precedence doesnt matter, so the code is easier to understand and verify than (int64_t)a * b thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB In a rich man's house there is no place to spit but his face. -- Diogenes of Sinope
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