static int dns_parse_callback(void *c, int rr, const void *data, int len, const void *packet)
 {
 	char tmp[256];
 	struct dpc_ctx *ctx = c;
 	switch (rr) {
 	case RR_A:
 		if (len != 4) return -1;
		ctx->addrs[ctx->cnt].scopeid = 0;
		memcpy(ctx->addrs[ctx->cnt++].addr, data, 4);
		break;
	case RR_AAAA:
		if (len != 16) return -1;
		ctx->addrs[ctx->cnt].family = AF_INET6;
		ctx->addrs[ctx->cnt].scopeid = 0;
		memcpy(ctx->addrs[ctx->cnt++].addr, data, 16);
		break;
	case RR_CNAME:
		if (__dn_expand(packet, (const unsigned char *)packet + 512,
		    data, tmp, sizeof tmp) > 0 && is_valid_hostname(tmp))
			strcpy(ctx->canon, tmp);
		break;
	}
	return 0;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.