[FFmpeg-cvslog] avcodec/exr: Check ac_count

[Michael Niedermayer]

ffmpeg | branch: release/4.4 | Michael Niedermayer <michael at niedermayer.cc> | Sun Aug  1 18:38:31 2021 +0200| [fbf576417aa7701fad87d27c998ab0fe2ec6ba84] | committer: Michael Niedermayer

avcodec/exr: Check ac_count

Fixes: signed integer overflow: -9223372036854775808 * 2 cannot be represented in type 'long long'
Fixes: 36244/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_EXR_fuzzer-6090656186499072

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 9bc32d7c4bed836086199ce55cf4a5ddd5217f3e)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=fbf576417aa7701fad87d27c998ab0fe2ec6ba84
---

 libavcodec/exr.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libavcodec/exr.c b/libavcodec/exr.c
index 27c243c12c..21b3b179ab 100644
--- a/libavcodec/exr.c
+++ b/libavcodec/exr.c
@@ -1014,7 +1014,9 @@ static int dwa_uncompress(EXRContext *s, const uint8_t *src, int compressed_size
     dc_count = AV_RL64(src + 72);
     ac_compression = AV_RL64(src + 80);
 
-    if (compressed_size < (uint64_t)(lo_size | ac_size | dc_size | rle_csize) || compressed_size < 88LL + lo_size + ac_size + dc_size + rle_csize)
+    if (   compressed_size < (uint64_t)(lo_size | ac_size | dc_size | rle_csize) || compressed_size < 88LL + lo_size + ac_size + dc_size + rle_csize
+        || ac_count > (uint64_t)INT_MAX/2
+    )
         return AVERROR_INVALIDDATA;
 
     bytestream2_init(&gb, src + 88, compressed_size - 88);