[FFmpeg-cvslog] libavformat/utils: consider avio_size() failure in ffio_limit()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Mon Nov  9 19:58:20 2020 +0100| [1b1dac2716d713dfd6949b7eb4a3c18c16f1faf6] | committer: Michael Niedermayer

libavformat/utils: consider avio_size() failure in ffio_limit()

Fixes: Timeout (>20sec -> 3ms)
Fixes: 26918/clusterfuzz-testcase-minimized-ffmpeg_dem_THP_fuzzer-5750425191710720

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=1b1dac2716d713dfd6949b7eb4a3c18c16f1faf6
---

 libavformat/utils.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/libavformat/utils.c b/libavformat/utils.c
index 8ac6bc04b8..f534b6e5b5 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -244,13 +244,16 @@ int av_format_get_probe_score(const AVFormatContext *s)
 int ffio_limit(AVIOContext *s, int size)
 {
     if (s->maxsize>= 0) {
-        int64_t remaining= s->maxsize - avio_tell(s);
+        int64_t pos = avio_tell(s);
+        int64_t remaining= s->maxsize - pos;
         if (remaining < size) {
             int64_t newsize = avio_size(s);
             if (!s->maxsize || s->maxsize<newsize)
                 s->maxsize = newsize - !newsize;
-            remaining= s->maxsize - avio_tell(s);
-            remaining= FFMAX(remaining, 0);
+            if (pos > s->maxsize && s->maxsize >= 0)
+                s->maxsize = AVERROR(EIO);
+            if (s->maxsize >= 0)
+                remaining = s->maxsize - pos;
         }
 
         if (s->maxsize >= 0 && remaining < size && size > 1) {