[FFmpeg-devel] [PATCH] avcodec/webp: Reinitilaize VP8 decoder on pixel format mismatch

[Michael Niedermayer]

Fixes: out of array access
Fixes: 1434/clusterfuzz-testcase-minimized-6314998085189632
Fixes: 1435/clusterfuzz-testcase-minimized-6483783723253760

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavcodec/webp.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/libavcodec/webp.c b/libavcodec/webp.c
index 16c3ae2662..23ed4bc26f 100644
--- a/libavcodec/webp.c
+++ b/libavcodec/webp.c
@@ -1330,12 +1330,17 @@ static int vp8_lossy_decode_frame(AVCodecContext *avctx, AVFrame *p,
     WebPContext *s = avctx->priv_data;
     AVPacket pkt;
     int ret;
+    enum AVPixelFormat wanted_pix_fmt = s->has_alpha ? AV_PIX_FMT_YUVA420P : AV_PIX_FMT_YUV420P;
+
+    if (s->initialized && wanted_pix_fmt != avctx->pix_fmt) {
+        ff_vp8_decode_free(avctx);
+        s->initialized = 0;
+    }
 
     if (!s->initialized) {
         ff_vp8_decode_init(avctx);
         s->initialized = 1;
-        if (s->has_alpha)
-            avctx->pix_fmt = AV_PIX_FMT_YUVA420P;
+        avctx->pix_fmt = wanted_pix_fmt;
     }
     s->lossless = 0;
 
-- 
2.11.0