[FFmpeg-cvslog] avcodec/cllc: Check num_bits

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu May 11 18:39:33 2017 +0200| [2bfd0a97587d26c0c39413a6291ccc66e4a928d0] | committer: Michael Niedermayer

avcodec/cllc: Check num_bits

Fixes: runtime error: shift exponent -2 is negative
Fixes: 1479/clusterfuzz-testcase-minimized-6638493360979968

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=2bfd0a97587d26c0c39413a6291ccc66e4a928d0
---

 libavcodec/cllc.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/libavcodec/cllc.c b/libavcodec/cllc.c
index b53e2c539c..933144ae81 100644
--- a/libavcodec/cllc.c
+++ b/libavcodec/cllc.c
@@ -56,6 +56,13 @@ static int read_code_table(CLLCContext *ctx, GetBitContext *gb, VLC *vlc)
 
     num_lens = get_bits(gb, 5);
 
+    if (num_lens > VLC_BITS * VLC_DEPTH) {
+        vlc->table = NULL;
+
+        av_log(ctx->avctx, AV_LOG_ERROR, "To long VLCs %d\n", num_lens);
+        return AVERROR_INVALIDDATA;
+    }
+
     for (i = 0; i < num_lens; i++) {
         num_codes      = get_bits(gb, 9);
         num_codes_sum += num_codes;