sws-test: check W/H

Fixes CID733834
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libswscale/swscale-test.c

@@ -316,7 +316,8 @@ static int fileTest(uint8_t *ref[4], int refStride[4], int w, int h, FILE *fp,
         srcFormat = av_get_pix_fmt(srcStr);
         dstFormat = av_get_pix_fmt(dstStr);
 
-        if (srcFormat == AV_PIX_FMT_NONE || dstFormat == AV_PIX_FMT_NONE) {
+        if (srcFormat == AV_PIX_FMT_NONE || dstFormat == AV_PIX_FMT_NONE ||
+            srcW > 1024U || srcH > 1024U || dstW > 1024U || dstH > 1024U) {
             fprintf(stderr, "malformed input file\n");
             return -1;
         }