On Sat, 30 Sep 2023, Michael Niedermayer wrote:
Fixes: signed integer overflow: 109817402400 * 301990077 cannot be represented
in type 'long long'
Fixes:
51896/clusterfuzz-testcase-minimized-ffmpeg_dem_AVI_fuzzer-6706191715139584
Found-by: continuous fuzzing process
https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
---
libavformat/avidec.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/libavformat/avidec.c b/libavformat/avidec.c
index 00bd7a98a9d..cfc693842b7 100644
--- a/libavformat/avidec.c
+++ b/libavformat/avidec.c
@@ -27,6 +27,7 @@
#include "libavutil/avstring.h"
#include "libavutil/opt.h"
#include "libavutil/dict.h"
+#include "libavutil/integer.h"
#include "libavutil/internal.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mathematics.h"
@@ -476,7 +477,7 @@ static int calculate_bitrate(AVFormatContext *s)
AVStream *st = s->streams[i];
FFStream *const sti = ffstream(st);
int64_t duration;
- int64_t bitrate;
+ int64_t bitrate = 0;
for (j = 0; j < sti->nb_index_entries; j++)
len += sti->index_entries[j].size;
@@ -484,7 +485,14 @@ static int calculate_bitrate(AVFormatContext *s)
if (sti->nb_index_entries < 2 || st->codecpar->bit_rate > 0)
continue;
duration = sti->index_entries[j-1].timestamp -
sti->index_entries[0].timestamp;
- bitrate = av_rescale(8*len, st->time_base.den, duration *
st->time_base.num);
+ if (INT64_MAX / duration >= st->time_base.num) {
+ bitrate = av_rescale(8*len, st->time_base.den, duration *
st->time_base.num);
Why not always use the AVInteger version? This is not performance
sensitive as far as I see.
Regards,
Marton
+ } else {
+ AVInteger bitrate_i = av_div_i(av_mul_i(av_int2i(8*len),
av_int2i(st->time_base.den)),
+ av_mul_i(av_int2i(duration),
av_int2i(st->time_base.num)));
+ if (av_cmp_i(bitrate_i, av_int2i(INT64_MAX)) <= 0)
+ bitrate = av_i2int(bitrate_i);
+ }
if (bitrate > 0) {
st->codecpar->bit_rate = bitrate;
}
--
2.17.1
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