avcodec/golomb: Speed up long ur_golomb codes
authorMichael Niedermayer <michael@niedermayer.cc>
Fri, 9 Nov 2018 20:50:23 +0000 (21:50 +0100)
committerMichael Niedermayer <michael@niedermayer.cc>
Tue, 13 Nov 2018 21:28:12 +0000 (22:28 +0100)
Fixes: Timeout
Fixes: 10972/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FLAC_fuzzer-5707569640243200

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

index 5c25883..fcc78f4 100644 (file)
@@ -476,15 +476,19 @@ static inline int get_ur_golomb_jpegls(GetBitContext *gb, int k, int limit,
         return buf;
     } else {
         int i;
-        for (i = 0; i < limit && SHOW_UBITS(re, gb, 1) == 0; i++) {
+        for (i = 0; i + MIN_CACHE_BITS <= limit && SHOW_UBITS(re, gb, MIN_CACHE_BITS) == 0; i += MIN_CACHE_BITS) {
             if (gb->size_in_bits <= re_index) {
                 CLOSE_READER(re, gb);
                 return -1;
             }
-            LAST_SKIP_BITS(re, gb, 1);
+            LAST_SKIP_BITS(re, gb, MIN_CACHE_BITS);
             UPDATE_CACHE(re, gb);
         }
-        SKIP_BITS(re, gb, 1);
+        for (; i < limit && SHOW_UBITS(re, gb, 1) == 0; i++) {
+            SKIP_BITS(re, gb, 1);
+        }
+        LAST_SKIP_BITS(re, gb, 1);
+        UPDATE_CACHE(re, gb);
 
         if (i < limit - 1) {
             if (k) {