[FFmpeg-devel] [PATCH 3/4] avcodec/apedec: Fix various integer overflows

[Michael Niedermayer]

Fixes: signed integer overflow: -538976267 * 31 cannot be represented in type 'int'
Fixes: left shift of 65312 by 16 places cannot be represented in type 'int'
Fixes: 15255/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APE_fuzzer-5718831688843264

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavcodec/apedec.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/libavcodec/apedec.c b/libavcodec/apedec.c
index 3558a5b708..61ebfdafd5 100644
--- a/libavcodec/apedec.c
+++ b/libavcodec/apedec.c
@@ -554,7 +554,7 @@ static inline int ape_decode_value_3990(APEContext *ctx, APERice *rice)
     overflow = range_get_symbol(ctx, counts_3980, counts_diff_3980);
 
     if (overflow == (MODEL_ELEMENTS - 1)) {
-        overflow  = range_decode_bits(ctx, 16) << 16;
+        overflow  = (unsigned)range_decode_bits(ctx, 16) << 16;
         overflow |= range_decode_bits(ctx, 16);
     }
 
@@ -1130,7 +1130,7 @@ static av_always_inline int predictor_update_filter(APEPredictor *p,
                   p->buf[delayA - 3] * (unsigned)p->coeffsA[filter][3];
 
     /*  Apply a scaled first-order filter compression */
-    p->buf[delayB]     = p->filterA[filter ^ 1] - ((p->filterB[filter] * 31) >> 5);
+    p->buf[delayB]     = p->filterA[filter ^ 1] - ((int)(p->filterB[filter] * 31U) >> 5);
     p->buf[adaptB]     = APESIGN(p->buf[delayB]);
     p->buf[delayB - 1] = p->buf[delayB] - p->buf[delayB - 1];
     p->buf[adaptB - 1] = APESIGN(p->buf[delayB - 1]);
@@ -1143,7 +1143,7 @@ static av_always_inline int predictor_update_filter(APEPredictor *p,
                   p->buf[delayB - 4] * (unsigned)p->coeffsB[filter][4];
 
     p->lastA[filter] = decoded + ((int)((unsigned)predictionA + (predictionB >> 1)) >> 10);
-    p->filterA[filter] = p->lastA[filter] + ((p->filterA[filter] * 31) >> 5);
+    p->filterA[filter] = p->lastA[filter] + ((int)(p->filterA[filter] * 31U) >> 5);
 
     sign = APESIGN(decoded);
     p->coeffsA[filter][0] += p->buf[adaptA    ] * sign;
-- 
2.21.0