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[FFmpeg-devel,3/4] avformat/mpc8: Check first keyframe position for overflow

Message ID 20210801193031.4094-3-michael@niedermayer.cc
State Accepted
Commit 2bbef69b0ba938cce4f9d61bed46d3f3058e56c2
Headers show
Series [FFmpeg-devel,1/4] tools/target_dec_fuzzer: check max samples in flush loop | expand

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andriy/x86_make success Make finished
andriy/x86_make_fate success Make fate finished
andriy/PPC64_make success Make finished
andriy/PPC64_make_fate success Make fate finished

Commit Message

Michael Niedermayer Aug. 1, 2021, 7:30 p.m. UTC 
Fixes: signed integer overflow: 9223372036854775791 + 18 cannot be represented in type 'long'
Fixes: 36307/clusterfuzz-testcase-minimized-ffmpeg_dem_MPC8_fuzzer-4917863877050368

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavformat/mpc8.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
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Patch

diff --git a/libavformat/mpc8.c b/libavformat/mpc8.c
index df5d345f85..a0e661c2ab 100644
--- a/libavformat/mpc8.c
+++ b/libavformat/mpc8.c
@@ -177,7 +177,13 @@  static void mpc8_parse_seektable(AVFormatContext *s, int64_t off)
     }
     seekd = get_bits(&gb, 4);
     for(i = 0; i < 2; i++){
-        pos = gb_get_v(&gb) + c->header_pos;
+        pos = gb_get_v(&gb);
+        if (av_sat_add64(pos, c->header_pos) != pos + (uint64_t)c->header_pos) {
+            av_free(buf);
+            return;
+        }
+
+        pos += c->header_pos;
         ppos[1 - i] = pos;
         av_add_index_entry(s->streams[0], pos, i, 0, 0, AVINDEX_KEYFRAME);
     }