
< 	dec->numtiles = dec->numhtiles * dec->numvtiles;
---
> 	long long numtiles = (long long)dec->numhtiles * dec->numvtiles;
> 	if (numtiles > INT_MAX) {
> 		// handle overflow error
> 	} else {
> 		dec->numtiles = (int)numtiles;
> 	}
