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[FFmpeg-devel,1/3] avformat/utils: Avoid overflow in codec_info_duration computation for subtitles

Message ID 20210610135811.21320-1-michael@niedermayer.cc
State Accepted
Commit ffe4851e2359e17c4406ab05e2e31fc7ef68de95
Headers show
Series [FFmpeg-devel,1/3] avformat/utils: Avoid overflow in codec_info_duration computation for subtitles | expand

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Commit Message

Michael Niedermayer June 10, 2021, 1:58 p.m. UTC 
Fixes: signed integer overflow: 9223126845747118112 - -2594073385365397472 cannot be represented in type 'long'
Fixes: 34936/clusterfuzz-testcase-minimized-ffmpeg_dem_MATROSKA_fuzzer-6739888002170880

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavformat/utils.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Michael Niedermayer June 12, 2021, 3:59 p.m. UTC | #1 
On Thu, Jun 10, 2021 at 03:58:09PM +0200, Michael Niedermayer wrote:
> Fixes: signed integer overflow: 9223126845747118112 - -2594073385365397472 cannot be represented in type 'long'
> Fixes: 34936/clusterfuzz-testcase-minimized-ffmpeg_dem_MATROSKA_fuzzer-6739888002170880
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavformat/utils.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

will apply patchset

[...]
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Patch

diff --git a/libavformat/utils.c b/libavformat/utils.c
index 0fc55c8da2..0c64a7c6fb 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -3843,7 +3843,9 @@  int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
                 break;
             }
             if (pkt->duration) {
-                if (avctx->codec_type == AVMEDIA_TYPE_SUBTITLE && pkt->pts != AV_NOPTS_VALUE && st->start_time != AV_NOPTS_VALUE && pkt->pts >= st->start_time) {
+                if (avctx->codec_type == AVMEDIA_TYPE_SUBTITLE && pkt->pts != AV_NOPTS_VALUE && st->start_time != AV_NOPTS_VALUE && pkt->pts >= st->start_time
+                    && (uint64_t)pkt->pts - st->start_time < INT64_MAX
+                ) {
                     st->internal->info->codec_info_duration = FFMIN(pkt->pts - st->start_time, st->internal->info->codec_info_duration + pkt->duration);
                 } else
                     st->internal->info->codec_info_duration += pkt->duration;