avcodec/sonic: Fix integer overflow in predictor_calc_error()

Fixes: signed integer overflow: 5 * -1094995529 cannot be represented in type 'int'
Fixes: 18346/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_SONIC_fuzzer-5709623893426176
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

diff --git a/libavcodec/sonic.c b/libavcodec/sonic.c
index 34d2952e69ce5304a7eb13964f72e9563f632a6e..219412eb77d947d50b26817da7ada5601fce5a79 100644 (file)
--- a/libavcodec/sonic.c
+++ b/libavcodec/sonic.c
@@ -473,7 +473,7 @@ static int predictor_calc_error(int *k, int *state, int order, int error)
     {
         int k_value = *k_ptr, state_value = *state_ptr;
         x -= shift_down(k_value * state_value, LATTICE_SHIFT);
-        state_ptr[1] = state_value + shift_down(k_value * x, LATTICE_SHIFT);
+        state_ptr[1] = state_value + shift_down(k_value * (unsigned)x, LATTICE_SHIFT);
     }
 #else
     for (i = order-2; i >= 0; i--)