[FFmpeg-cvslog] avcodec/agm: Check for too many too short codes in make_new_tree()
Michael Niedermayer
git at videolan.org
Mon Apr 22 01:51:06 EEST 2019
ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sun Apr 21 11:05:18 2019 +0200| [7ee7bb92e603c35b5467e4106583f5fe7ba9ba55] | committer: Michael Niedermayer
avcodec/agm: Check for too many too short codes in make_new_tree()
Fixes: SEGV on unknown address
Fixes: 14198/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AGM_fuzzer-5723579234123776
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=7ee7bb92e603c35b5467e4106583f5fe7ba9ba55
---
libavcodec/agm.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/libavcodec/agm.c b/libavcodec/agm.c
index f3d81bf163..c9d7be5521 100644
--- a/libavcodec/agm.c
+++ b/libavcodec/agm.c
@@ -919,7 +919,7 @@ static void get_tree_codes(uint32_t *codes, Node *nodes, int idx, uint32_t pfx,
}
}
-static void make_new_tree(const uint8_t *bitlens, uint32_t *codes)
+static int make_new_tree(const uint8_t *bitlens, uint32_t *codes)
{
int zlcount = 0, curlen, idx, nindex, last, llast;
int blcounts[32] = { 0 };
@@ -959,6 +959,9 @@ static void make_new_tree(const uint8_t *bitlens, uint32_t *codes)
int p = node_idx[nindex - 1 + 512];
int ch = syms[256 * curlen + i];
+ if (nindex <= 0)
+ return AVERROR_INVALIDDATA;
+
if (nodes[p].child[0] == -1) {
nodes[p].child[0] = ch;
} else {
@@ -998,6 +1001,7 @@ static void make_new_tree(const uint8_t *bitlens, uint32_t *codes)
next:
get_tree_codes(codes, nodes, 256, 0, 0);
+ return 0;
}
static int build_huff(const uint8_t *bitlen, VLC *vlc)
@@ -1008,7 +1012,9 @@ static int build_huff(const uint8_t *bitlen, VLC *vlc)
uint32_t codes[256];
int nb_codes = 0;
- make_new_tree(bitlen, new_codes);
+ int ret = make_new_tree(bitlen, new_codes);
+ if (ret < 0)
+ return ret;
for (int i = 0; i < 256; i++) {
if (bitlen[i]) {
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