[FFmpeg-cvslog] avcodec/wmalosslessdec: Fix several integer issues

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Mon Nov 18 14:22:57 2019 +0100| [ec3fe67074ad0a6a3a817f6f42175ea63a98092b] | committer: Michael Niedermayer

avcodec/wmalosslessdec: Fix several integer issues

Fixes: shift exponent -1 is negative (and others)
Fixes: 18852/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WMALOSSLESS_fuzzer-5660855295541248

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=ec3fe67074ad0a6a3a817f6f42175ea63a98092b
---

 libavcodec/wmalosslessdec.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/libavcodec/wmalosslessdec.c b/libavcodec/wmalosslessdec.c
index 9489338cef..7afadaae4a 100644
--- a/libavcodec/wmalosslessdec.c
+++ b/libavcodec/wmalosslessdec.c
@@ -678,7 +678,7 @@ static void mclms_predict(WmallDecodeCtx *s, int icoef, int *pred)
         for (i = 0; i < ich; i++)
             pred[ich] += (uint32_t)s->channel_residues[i][icoef] *
                          s->mclms_coeffs_cur[i + num_channels * ich];
-        pred[ich] += 1 << s->mclms_scaling - 1;
+        pred[ich] += (1 << s->mclms_scaling) >> 1;
         pred[ich] >>= s->mclms_scaling;
         s->channel_residues[ich][icoef] += pred[ich];
     }
@@ -811,19 +811,19 @@ static void revert_acfilter(WmallDecodeCtx *s, int tile_size)
             pred = 0;
             for (j = 0; j < order; j++) {
                 if (i <= j)
-                    pred += filter_coeffs[j] * prevvalues[j - i];
+                    pred += (uint32_t)filter_coeffs[j] * prevvalues[j - i];
                 else
-                    pred += s->channel_residues[ich][i - j - 1] * filter_coeffs[j];
+                    pred += (uint32_t)s->channel_residues[ich][i - j - 1] * filter_coeffs[j];
             }
             pred >>= scaling;
-            s->channel_residues[ich][i] += pred;
+            s->channel_residues[ich][i] += (unsigned)pred;
         }
         for (i = order; i < tile_size; i++) {
             pred = 0;
             for (j = 0; j < order; j++)
                 pred += (uint32_t)s->channel_residues[ich][i - j - 1] * filter_coeffs[j];
             pred >>= scaling;
-            s->channel_residues[ich][i] += pred;
+            s->channel_residues[ich][i] += (unsigned)pred;
         }
         for (j = 0; j < order; j++)
             prevvalues[j] = s->channel_residues[ich][tile_size - j - 1];