avcodec/sbrdsp_fixed: Fix undefined overflows in autocorrelate()

Fixes: runtime error: signed integer overflow: 8903997421129740175 + 354481484684609529 cannot be represented in type 'long'
Fixes: 2045/clusterfuzz-testcase-minimized-6751255865065472

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/sbrdsp_fixed.c

@@ -147,19 +147,19 @@ static av_always_inline void autocorrelate(const int x[40][2], SoftFloat phi[3][
 
     if (lag) {
         for (i = 1; i < 38; i++) {
-            accu_re += (int64_t)x[i][0] * x[i+lag][0];
-            accu_re += (int64_t)x[i][1] * x[i+lag][1];
-            accu_im += (int64_t)x[i][0] * x[i+lag][1];
-            accu_im -= (int64_t)x[i][1] * x[i+lag][0];
+            accu_re += (uint64_t)x[i][0] * x[i+lag][0];
+            accu_re += (uint64_t)x[i][1] * x[i+lag][1];
+            accu_im += (uint64_t)x[i][0] * x[i+lag][1];
+            accu_im -= (uint64_t)x[i][1] * x[i+lag][0];
         }
 
         real_sum = accu_re;
         imag_sum = accu_im;
 
-        accu_re += (int64_t)x[ 0][0] * x[lag][0];
-        accu_re += (int64_t)x[ 0][1] * x[lag][1];
-        accu_im += (int64_t)x[ 0][0] * x[lag][1];
-        accu_im -= (int64_t)x[ 0][1] * x[lag][0];
+        accu_re += (uint64_t)x[ 0][0] * x[lag][0];
+        accu_re += (uint64_t)x[ 0][1] * x[lag][1];
+        accu_im += (uint64_t)x[ 0][0] * x[lag][1];
+        accu_im -= (uint64_t)x[ 0][1] * x[lag][0];
 
         phi[2-lag][1][0] = autocorr_calc(accu_re);
         phi[2-lag][1][1] = autocorr_calc(accu_im);
@@ -167,28 +167,28 @@ static av_always_inline void autocorrelate(const int x[40][2], SoftFloat phi[3][
         if (lag == 1) {
             accu_re = real_sum;
             accu_im = imag_sum;
-            accu_re += (int64_t)x[38][0] * x[39][0];
-            accu_re += (int64_t)x[38][1] * x[39][1];
-            accu_im += (int64_t)x[38][0] * x[39][1];
-            accu_im -= (int64_t)x[38][1] * x[39][0];
+            accu_re += (uint64_t)x[38][0] * x[39][0];
+            accu_re += (uint64_t)x[38][1] * x[39][1];
+            accu_im += (uint64_t)x[38][0] * x[39][1];
+            accu_im -= (uint64_t)x[38][1] * x[39][0];
 
             phi[0][0][0] = autocorr_calc(accu_re);
             phi[0][0][1] = autocorr_calc(accu_im);
         }
     } else {
         for (i = 1; i < 38; i++) {
-            accu_re += (int64_t)x[i][0] * x[i][0];
-            accu_re += (int64_t)x[i][1] * x[i][1];
+            accu_re += (uint64_t)x[i][0] * x[i][0];
+            accu_re += (uint64_t)x[i][1] * x[i][1];
         }
         real_sum = accu_re;
-        accu_re += (int64_t)x[ 0][0] * x[ 0][0];
-        accu_re += (int64_t)x[ 0][1] * x[ 0][1];
+        accu_re += (uint64_t)x[ 0][0] * x[ 0][0];
+        accu_re += (uint64_t)x[ 0][1] * x[ 0][1];
 
         phi[2][1][0] = autocorr_calc(accu_re);
 
         accu_re = real_sum;
-        accu_re += (int64_t)x[38][0] * x[38][0];
-        accu_re += (int64_t)x[38][1] * x[38][1];
+        accu_re += (uint64_t)x[38][0] * x[38][0];
+        accu_re += (uint64_t)x[38][1] * x[38][1];
 
         phi[1][0][0] = autocorr_calc(accu_re);
     }