avcodec/fic: Fix multiple runtime error: signed integer overflow: 5793 *...

avcodec/fic: Fix multiple runtime error: signed integer overflow: 5793 * 419752 cannot be represented in type 'int'

Fixes: 1669/clusterfuzz-testcase-minimized-5287529198649344

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

libavcodec/fic.c

@@ -89,22 +89,22 @@ static av_always_inline void fic_idct(int16_t *blk, int step, int shift, int rnd
     const int t1 =  27246 * blk[5 * step] - 18405 * blk[3 * step];
     const int t2 =   6393 * blk[7 * step] + 32139 * blk[1 * step];
     const int t3 =   6393 * blk[1 * step] - 32139 * blk[7 * step];
-    const int t4 = 5793 * (t2 + t0 + 0x800 >> 12);
-    const int t5 = 5793 * (t3 + t1 + 0x800 >> 12);
-    const int t6 = t2 - t0;
-    const int t7 = t3 - t1;
-    const int t8 =  17734 * blk[2 * step] - 42813 * blk[6 * step];
-    const int t9 =  17734 * blk[6 * step] + 42814 * blk[2 * step];
-    const int tA = (blk[0 * step] - blk[4 * step]) * 32768 + rnd;
-    const int tB = (blk[0 * step] + blk[4 * step]) * 32768 + rnd;
-    blk[0 * step] = (  t4       + t9 + tB) >> shift;
-    blk[1 * step] = (  t6 + t7  + t8 + tA) >> shift;
-    blk[2 * step] = (  t6 - t7  - t8 + tA) >> shift;
-    blk[3 * step] = (  t5       - t9 + tB) >> shift;
-    blk[4 * step] = ( -t5       - t9 + tB) >> shift;
-    blk[5 * step] = (-(t6 - t7) - t8 + tA) >> shift;
-    blk[6 * step] = (-(t6 + t7) + t8 + tA) >> shift;
-    blk[7 * step] = ( -t4       + t9 + tB) >> shift;
+    const unsigned t4 = 5793U * (t2 + t0 + 0x800 >> 12);
+    const unsigned t5 = 5793U * (t3 + t1 + 0x800 >> 12);
+    const unsigned t6 = t2 - t0;
+    const unsigned t7 = t3 - t1;
+    const unsigned t8 =  17734 * blk[2 * step] - 42813 * blk[6 * step];
+    const unsigned t9 =  17734 * blk[6 * step] + 42814 * blk[2 * step];
+    const unsigned tA = (blk[0 * step] - blk[4 * step]) * 32768 + rnd;
+    const unsigned tB = (blk[0 * step] + blk[4 * step]) * 32768 + rnd;
+    blk[0 * step] = (int)(  t4       + t9 + tB) >> shift;
+    blk[1 * step] = (int)(  t6 + t7  + t8 + tA) >> shift;
+    blk[2 * step] = (int)(  t6 - t7  - t8 + tA) >> shift;
+    blk[3 * step] = (int)(  t5       - t9 + tB) >> shift;
+    blk[4 * step] = (int)( -t5       - t9 + tB) >> shift;
+    blk[5 * step] = (int)(-(t6 - t7) - t8 + tA) >> shift;
+    blk[6 * step] = (int)(-(t6 + t7) + t8 + tA) >> shift;
+    blk[7 * step] = (int)( -t4       + t9 + tB) >> shift;
 }
 
 static void fic_idct_put(uint8_t *dst, int stride, int16_t *block)