[FFmpeg-cvslog] avcodec/scpr: Test bx before use

[Michael Niedermayer]

ffmpeg | branch: release/4.1 | Michael Niedermayer <michael at niedermayer.cc> | Sun Jan  8 20:03:40 2023 +0100| [dd507e4c8f1596ae3d84eec2477532fef0d046df] | committer: Michael Niedermayer

avcodec/scpr: Test bx before use

Fixes: out of array access on 32bit
Fixes: 54850/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_SCPR_fuzzer-5302669294305280

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 1b59de3770b2e3f7f44ec4adba27c88b79adaaec)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=dd507e4c8f1596ae3d84eec2477532fef0d046df
---

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

diff --git a/libavcodec/scpr.c b/libavcodec/scpr.c
index 297fb315e2..a2d5bb6514 100644
--- a/libavcodec/scpr.c
+++ b/libavcodec/scpr.c
@@ -592,6 +592,9 @@ static int decompress_p(AVCodecContext *avctx,
                 int run, z, bx = x * 16 + sx1, by = y * 16 + sy1;
                 unsigned r, g, b, clr, ptype = 0;
 
+                if (bx >= avctx->width)
+                    return AVERROR_INVALIDDATA;
+
                 for (; by < y * 16 + sy2 && by < avctx->height;) {
                     ret = decode_value(s, s->op_model[ptype], 6, 1000, &ptype);
                     if (ret < 0)