[FFmpeg-cvslog] avcodec/webp: Check ref_x/y

[Michael Niedermayer]

ffmpeg | branch: release/4.3 | Michael Niedermayer <michael at niedermayer.cc> | Fri Aug 16 16:00:01 2024 +0200| [daa0d94cf9965f4137d2e3c0492c62849888f806] | committer: Michael Niedermayer

avcodec/webp: Check ref_x/y

Fixes: 70991/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WEBP_fuzzer-5544067620995072
Fixes: use of uninintailized value

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 7c1e732ad2e240af5afe9ffea443c91bb233aa65)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=daa0d94cf9965f4137d2e3c0492c62849888f806
---

 libavcodec/webp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavcodec/webp.c b/libavcodec/webp.c
index ae16b85f46..3a9cedd47f 100644
--- a/libavcodec/webp.c
+++ b/libavcodec/webp.c
@@ -739,6 +739,9 @@ static int decode_entropy_coded_image(WebPContext *s, enum ImageRole role,
             ref_x = FFMAX(0, ref_x);
             ref_y = FFMAX(0, ref_y);
 
+            if (ref_y == y && ref_x >= x)
+                return AVERROR_INVALIDDATA;
+
             /* copy pixels
              * source and dest regions can overlap and wrap lines, so just
              * copy per-pixel */