swresample/resample: Limit filter length

Related to CID1197063

The limit choosen is arbitrary and much larger than what makes sense.
It avoids the need for checking arithmetic operations with the length for overflow
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libswresample/resample.c

@@ -229,6 +229,11 @@ static ResampleContext *resample_init(ResampleContext *c, int out_rate, int in_r
             av_assert0(0);
         }
 
+        if (filter_size/factor > INT32_MAX/256) {
+            av_log(NULL, AV_LOG_ERROR, "Filter length too large\n");
+            goto error;
+        }
+
         c->phase_shift   = phase_shift;
         c->phase_mask    = phase_count - 1;
         c->linear        = linear;