[FFmpeg-cvslog] avcodec/rka: use unsigned for buf0 additions

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu Jun  8 15:05:50 2023 +0200| [e736238b35a1e0f69fe8e5a9a7359ba24883c488] | committer: Michael Niedermayer

avcodec/rka: use unsigned for buf0 additions

Fixes: signed integer overflow: -38912000 + -2109276160 cannot be represented in type 'int'
Fixes: 59670/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_RKA_fuzzer-4987563245699072

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=e736238b35a1e0f69fe8e5a9a7359ba24883c488
---

 libavcodec/rka.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/rka.c b/libavcodec/rka.c
index 76dca52602..d56f4faee4 100644
--- a/libavcodec/rka.c
+++ b/libavcodec/rka.c
@@ -735,10 +735,10 @@ static int decode_filter(RKAContext *s, ChContext *ctx, ACoder *ac, int off, uns
                     ctx->buf1[off] = (val + (sum >> bits)) * (1U << bits) +
                         (((1U << bits) - 1U) & ctx->buf1[off + -1]);
                 }
-                ctx->buf0[off] = ctx->buf1[off] + ctx->buf0[off + -1];
+                ctx->buf0[off] = ctx->buf1[off] + (unsigned)ctx->buf0[off + -1];
             } else {
                 val *= 1U << ctx->cmode;
-                sum += ctx->buf0[off + -1] + val;
+                sum += ctx->buf0[off + -1] + (unsigned)val;
                 switch (s->bps) {
                 case 16: sum = av_clip_int16(sum); break;
                 case  8: sum = av_clip_int8(sum);  break;