datastore: fix get query caching

[crozzy]

This change replaces caching the DB pgx.Rows, which is an iterator, with the actual potential vulnerabilities. Previously, subsequent records manifesting in the same query were given a pgx.Rows object that had been exhausted.

[crozzy]

Post-change:

    "186": {
      "id": "186",
      "name": "xz-libs",
      "version": "5.2.2-1.el7",
      "kind": "binary",
      "source": {
        "id": "185",
        "name": "xz",
        "version": "5.2.2-1.el7",
        "kind": "source"
      },
      "arch": "x86_64"
    },
...
    "1924": {
      "id": "1924",
      "name": "xz-libs",
      "version": "5.2.2-1.el7",
      "kind": "binary",
      "source": {
        "id": "185",
        "name": "xz",
        "version": "5.2.2-1.el7",
        "kind": "source"
      },
      "arch": "i686"
    },
...
    "2675687": {
      "id": "2675687",
      "updater": "rhel-vex",
      "name": "CVE-2022-1271",
      "description": "An arbitrary file write vulnerability was found in GNU gzip's zgrep utility. When zgrep is applied on the attacker's chosen file name (for example, a crafted file name), this can overwrite an attacker's content to an arbitrary attacker-selected file. This flaw occurs due to insufficient validation when processing filenames with two or more newlines where selected content and the target file names are embedded in crafted multi-line file names. This flaw allows a remote, low privileged attacker to force zgrep to write arbitrary files on the system.",
      "issued": "2022-04-07T00:00:00Z",
      "links": "https://access.redhat.com/security/cve/CVE-2022-1271 https://bugzilla.redhat.com/show_bug.cgi?id=2073310 https://www.cve.org/CVERecord?id=CVE-2022-1271 https://nvd.nist.gov/vuln/detail/CVE-2022-1271 https://security.access.redhat.com/data/csaf/v2/vex/2022/cve-2022-1271.json https://access.redhat.com/errata/RHSA-2022:5052",
      "severity": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "normalized_severity": "High",
      "package": {
        "id": "",
        "name": "xz-libs",
        "version": "",
        "kind": "binary",
        "arch": "i686|ppc|ppc64|ppc64le|s390|s390x|amd64|x86_64"
      },
      "distribution": {
        "id": "",
        "did": "",
        "name": "",
        "version": "",
        "version_code_name": "",
        "version_id": "",
        "arch": "",
        "cpe": "",
        "pretty_name": ""
      },
      "repository": {
        "name": "cpe:2.3:o:redhat:enterprise_linux:7:*:server:*:*:*:*:*",
        "key": "rhel-cpe-repository",
        "cpe": "cpe:2.3:o:redhat:enterprise_linux:7:*:server:*:*:*:*:*"
      },
      "fixed_in_version": "0:5.2.2-2.el7_9",
      "arch_op": "pattern match"
    },
...
"package_vulnerabilities": {
    "186": [
      "2675687"
    ],
...
    "1924": [
      "2675687"
    ],
}

[crozzy]

@hdonnay sorry just had to update

[RTann]

I think we are missing a rows.Close() at the end of the for rows.Next() loop

[RTann]

I get why it was done this way (avoids more indentations for the larger block after this), but it is a bit unfortunate we do the same exact thing after the for rows.Next() loop.

I'm wondering if we should explore making a separate function for the outer loop and inner loop so we can also defer some Close calls