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@niedermayer.cc>

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) {