avcodec/lagarith: Fix runtime error: left shift of negative value -1

Fixes: 1424/clusterfuzz-testcase-minimized-6088327159611392
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

diff --git a/libavcodec/lagarith.c b/libavcodec/lagarith.c
index 469eec42327c8fffc964b58f87a508f3e2375a07..044497720fa38a2fb2cb5afa0793c041951bb4d0 100644 (file)
--- a/libavcodec/lagarith.c
+++ b/libavcodec/lagarith.c
@@ -98,7 +98,7 @@ static uint32_t softfloat_mul(uint32_t x, uint64_t mantissa)
 
 static uint8_t lag_calc_zero_run(int8_t x)
 {
-    return (x << 1) ^ (x >> 7);
+    return (x * 2) ^ (x >> 7);
 }
 
 static int lag_decode_prob(GetBitContext *gb, uint32_t *value)