[FFmpeg-cvslog] avcodec/mobiclip: Check quantizer before table setup

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu Sep 10 23:59:53 2020 +0200| [bad8b17a3da219777341acafd3e3113ea2477484] | committer: Michael Niedermayer

avcodec/mobiclip: Check quantizer before table setup

Fixes: index -1 out of bounds for type 'const uint8_t [6][16]'
Fixes: out of array read
Fixes: shift exponent -21 is negative
Fixes: 25422/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MOBICLIP_fuzzer-5748258226569216
Fixes: shift exponent 8039082 is too large for 32-bit type 'int'
Fixes: 25430/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MOBICLIP_fuzzer-5698567770210304

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=bad8b17a3da219777341acafd3e3113ea2477484
---

 libavcodec/mobiclip.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/libavcodec/mobiclip.c b/libavcodec/mobiclip.c
index d147eddbae..13f0edc89d 100644
--- a/libavcodec/mobiclip.c
+++ b/libavcodec/mobiclip.c
@@ -1323,6 +1323,10 @@ static int mobiclip_decode(AVCodecContext *avctx, void *data,
         }
     } else {
         MotionXY *motion = s->motion;
+        int quantizer = s->quantizer + get_se_golomb(gb);
+
+        if (quantizer < 12 || quantizer > 161)
+            return AVERROR_INVALIDDATA;
 
         memset(motion, 0, s->motion_size);
 
@@ -1330,7 +1334,7 @@ static int mobiclip_decode(AVCodecContext *avctx, void *data,
         frame->key_frame = 0;
         s->dct_tab_idx = 0;
 
-        setup_qtables(avctx, s->quantizer + get_se_golomb(gb));
+        setup_qtables(avctx, quantizer);
         for (int y = 0; y < avctx->height; y += 16) {
             for (int x = 0; x < avctx->width; x += 16) {
                 int idx;