[FFmpeg-cvslog] avformat/iff: Saturate avio_tell() + 12

[Michael Niedermayer]

ffmpeg | branch: release/6.0 | Michael Niedermayer <michael at niedermayer.cc> | Sat Sep 30 00:56:06 2023 +0200| [73efebad01751c825f2416f7688105a6c938388b] | committer: Michael Niedermayer

avformat/iff: Saturate avio_tell() + 12

Fixes: signed integer overflow: 9223372036854775796 + 12 cannot be represented in type 'long long'
Fixes: 51896/clusterfuzz-testcase-minimized-ffmpeg_dem_IFF_fuzzer-4898373660704768

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 b8e754525ca3d3fd835f7360e11f29b02b39cd62)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=73efebad01751c825f2416f7688105a6c938388b
---

 libavformat/iff.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavformat/iff.c b/libavformat/iff.c
index b8e8bffe03..5bff0e9b6c 100644
--- a/libavformat/iff.c
+++ b/libavformat/iff.c
@@ -217,7 +217,7 @@ static int parse_dsd_diin(AVFormatContext *s, AVStream *st, uint64_t eof)
 {
     AVIOContext *pb = s->pb;
 
-    while (avio_tell(pb) + 12 <= eof && !avio_feof(pb)) {
+    while (av_sat_add64(avio_tell(pb), 12) <= eof && !avio_feof(pb)) {
         uint32_t tag      = avio_rl32(pb);
         uint64_t size     = avio_rb64(pb);
         uint64_t orig_pos = avio_tell(pb);
@@ -254,7 +254,7 @@ static int parse_dsd_prop(AVFormatContext *s, AVStream *st, uint64_t eof)
     int dsd_layout[6];
     ID3v2ExtraMeta *id3v2_extra_meta;
 
-    while (avio_tell(pb) + 12 <= eof && !avio_feof(pb)) {
+    while (av_sat_add64(avio_tell(pb), 12) <= eof && !avio_feof(pb)) {
         uint32_t tag      = avio_rl32(pb);
         uint64_t size     = avio_rb64(pb);
         uint64_t orig_pos = avio_tell(pb);