[FFmpeg-devel] [PATCH] avcodec/flac_parser: Do not loose header count in find_headers_search()

Michael Niedermayer michael at niedermayer.cc
Tue Feb 4 00:57:20 EET 2020


Fixes: Timeout
Fixes: out of array access
Fixes: 20274/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FLAC_fuzzer-5649631988154368
Fixes: 19275/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FLAC_fuzzer-5757535722405888

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/flac_parser.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/libavcodec/flac_parser.c b/libavcodec/flac_parser.c
index 9ffa288548..3424583c49 100644
--- a/libavcodec/flac_parser.c
+++ b/libavcodec/flac_parser.c
@@ -208,16 +208,20 @@ static int find_headers_search(FLACParseContext *fpc, uint8_t *buf,
     uint32_t x;
 
     for (i = 0; i < mod_offset; i++) {
-        if ((AV_RB16(buf + i) & 0xFFFE) == 0xFFF8)
-            size = find_headers_search_validate(fpc, search_start + i);
+        if ((AV_RB16(buf + i) & 0xFFFE) == 0xFFF8) {
+            int ret = find_headers_search_validate(fpc, search_start + i);
+            size = FFMAX(size, ret);
+        }
     }
 
     for (; i < buf_size - 1; i += 4) {
         x = AV_RN32(buf + i);
         if (((x & ~(x + 0x01010101)) & 0x80808080)) {
             for (j = 0; j < 4; j++) {
-                if ((AV_RB16(buf + i + j) & 0xFFFE) == 0xFFF8)
-                    size = find_headers_search_validate(fpc, search_start + i + j);
+                if ((AV_RB16(buf + i + j) & 0xFFFE) == 0xFFF8) {
+                    int ret = find_headers_search_validate(fpc, search_start + i + j);
+                    size = FFMAX(size, ret);
+                }
             }
         }
     }
-- 
2.17.1



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