[FFmpeg-cvslog] avcodec/alsdec: Fix integer overflow of raw_samples in decode_blocks()

[Michael Niedermayer]

ffmpeg | branch: release/4.2 | Michael Niedermayer <michael at niedermayer.cc> | Fri Jul 26 14:33:14 2019 +0200| [7e9bb72dd6eec7b5aead2fdb0d3ecea2df2029e4] | committer: Michael Niedermayer

avcodec/alsdec: Fix integer overflow of raw_samples in decode_blocks()

Fixes: signed integer overflow: 2147483424 - -1772303236 cannot be represented in type 'int'
Fixes: 15708/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALS_fuzzer-5067890362941440

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 ce652324062a2c72f92e40699797630ef7f1ec5a)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=7e9bb72dd6eec7b5aead2fdb0d3ecea2df2029e4
---

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

diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
index e1449a72a5..b8e4b3dc81 100644
--- a/libavcodec/alsdec.c
+++ b/libavcodec/alsdec.c
@@ -1175,10 +1175,10 @@ static int decode_blocks(ALSDecContext *ctx, unsigned int ra_frame,
                 av_log(ctx->avctx, AV_LOG_WARNING, "Invalid channel pair.\n");
 
             for (s = 0; s < div_blocks[b]; s++)
-                bd[0].raw_samples[s] = bd[1].raw_samples[s] - bd[0].raw_samples[s];
+                bd[0].raw_samples[s] = bd[1].raw_samples[s] - (unsigned)bd[0].raw_samples[s];
         } else if (bd[1].js_blocks) {
             for (s = 0; s < div_blocks[b]; s++)
-                bd[1].raw_samples[s] = bd[1].raw_samples[s] + bd[0].raw_samples[s];
+                bd[1].raw_samples[s] = bd[1].raw_samples[s] + (unsigned)bd[0].raw_samples[s];
         }
 
         offset  += div_blocks[b];