[FFmpeg-devel] [PATCH] avcodec/vp3: Check that there will be sufficient input for the coded fragments in unpack_superblocks()

[Michael Niedermayer]

Fixes: Timeout
Fixes: 6292/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VP3_fuzzer-4871218218926080

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavcodec/vp3.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/libavcodec/vp3.c b/libavcodec/vp3.c
index 1d83753314..fcc19a627b 100644
--- a/libavcodec/vp3.c
+++ b/libavcodec/vp3.c
@@ -543,7 +543,11 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
                                          : s->y_superblock_count);
         int num_coded_frags = 0;
 
-        for (i = sb_start; i < sb_end && get_bits_left(gb) > 0; i++) {
+        for (i = sb_start; i < sb_end; i++) {
+            if (get_bits_left(gb) < ((s->total_num_coded_frags + num_coded_frags) >> 2)) {
+                av_log(s->avctx, AV_LOG_ERROR, "Insufficient input data for coded fragments\n");
+                return AVERROR_INVALIDDATA;
+            }
             /* iterate through all 16 fragments in a superblock */
             for (j = 0; j < 16; j++) {
                 /* if the fragment is in bounds, check its coding status */
-- 
2.17.0