avcodec/iff: Check available space before entering loop in decode_long_vertical_delta...

Fixes: Timeout (31sec -> 41ms)
Fixes: 18380/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_IFF_ILBM_fuzzer-5645210121404416
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

diff --git a/libavcodec/iff.c b/libavcodec/iff.c
index c18bac1ea18a558f4897940aceae88953feb36dc..500f9bf3671779e2fd1e005bc28e4b0adc20d86e 100644 (file)
--- a/libavcodec/iff.c
+++ b/libavcodec/iff.c
@@ -1143,6 +1143,9 @@ static void decode_long_vertical_delta(uint8_t *dst,
                         x = bytestream2_get_be32(&dgb);
                     }
 
+                    if (ofsdst + (opcode - 1LL) * dstpitch > bytestream2_size_p(&pb))
+                        return;
+
                     while (opcode) {
                         bytestream2_seek_p(&pb, ofsdst, SEEK_SET);
                         if (h && (j == (ncolumns - 1))) {
@@ -1283,6 +1286,9 @@ static void decode_long_vertical_delta2(uint8_t *dst,
                         x = bytestream2_get_be32(&gb);
                     }
 
+                    if (ofsdst + (opcode - 1LL) * dstpitch > bytestream2_size_p(&pb))
+                        return;
+
                     while (opcode && bytestream2_get_bytes_left_p(&pb) > 1) {
                         bytestream2_seek_p(&pb, ofsdst, SEEK_SET);
                         if (h && (j == ncolumns - 1))