swscale/swscale: Add some sanity checks for srcSlice* parameters

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libswscale/swscale.c

@@ -1048,12 +1048,20 @@ int attribute_align_arg sws_scale(struct SwsContext *c,
     const uint8_t *src2[4];
     uint8_t *dst2[4];
     uint8_t *rgb0_tmp = NULL;
+    int macro_height = isBayer(c->srcFormat) ? 2 : (1 << c->chrSrcVSubSample);
 
     if (!srcStride || !dstStride || !dst || !srcSlice) {
         av_log(c, AV_LOG_ERROR, "One of the input parameters to sws_scale() is NULL, please check the calling code\n");
         return 0;
     }
 
+    if ((srcSliceY & (macro_height-1)) ||
+        ((srcSliceH& (macro_height-1)) && srcSliceY + srcSliceH != c->srcH) ||
+        srcSliceY + srcSliceH > c->srcH) {
+        av_log(c, AV_LOG_ERROR, "Slice parameters %d, %d are invalid\n", srcSliceY, srcSliceH);
+        return AVERROR(EINVAL);
+    }
+
     if (c->gamma_flag && c->cascaded_context[0]) {