ghsa-6vh7-f36j-r556
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nft_set_pipapo: do not free live element
Pablo reports a crash with large batches of elements with a back-to-back add/remove pattern. Quoting Pablo:
add_elem("00000000") timeout 100 ms ... add_elem("0000000X") timeout 100 ms del_elem("0000000X") <---------------- delete one that was just added ... add_elem("00005000") timeout 100 ms
1) nft_pipapo_remove() removes element 0000000X Then, KASAN shows a splat.
Looking at the remove function there is a chance that we will drop a rule that maps to a non-deactivated element.
Removal happens in two steps, first we do a lookup for key k and return the to-be-removed element and mark it as inactive in the next generation. Then, in a second step, the element gets removed from the set/map.
The _remove function does not work correctly if we have more than one element that share the same key.
This can happen if we insert an element into a set when the set already holds an element with same key, but the element mapping to the existing key has timed out or is not active in the next generation.
In such case its possible that removal will unmap the wrong element. If this happens, we will leak the non-deactivated element, it becomes unreachable.
The element that got deactivated (and will be freed later) will remain reachable in the set data structure, this can result in a crash when such an element is retrieved during lookup (stale pointer).
Add a check that the fully matching key does in fact map to the element that we have marked as inactive in the deactivation step. If not, we need to continue searching.
Add a bug/warn trap at the end of the function as well, the remove function must not ever be called with an invisible/unreachable/non-existent element.
v2: avoid uneeded temporary variable (Stefano)
{
"affected": [],
"aliases": [
"CVE-2024-26924"
],
"database_specific": {
"cwe_ids": [
"CWE-476"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-04-25T06:15:57Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_set_pipapo: do not free live element\n\nPablo reports a crash with large batches of elements with a\nback-to-back add/remove pattern. Quoting Pablo:\n\n add_elem(\"00000000\") timeout 100 ms\n ...\n add_elem(\"0000000X\") timeout 100 ms\n del_elem(\"0000000X\") \u003c---------------- delete one that was just added\n ...\n add_elem(\"00005000\") timeout 100 ms\n\n 1) nft_pipapo_remove() removes element 0000000X\n Then, KASAN shows a splat.\n\nLooking at the remove function there is a chance that we will drop a\nrule that maps to a non-deactivated element.\n\nRemoval happens in two steps, first we do a lookup for key k and return the\nto-be-removed element and mark it as inactive in the next generation.\nThen, in a second step, the element gets removed from the set/map.\n\nThe _remove function does not work correctly if we have more than one\nelement that share the same key.\n\nThis can happen if we insert an element into a set when the set already\nholds an element with same key, but the element mapping to the existing\nkey has timed out or is not active in the next generation.\n\nIn such case its possible that removal will unmap the wrong element.\nIf this happens, we will leak the non-deactivated element, it becomes\nunreachable.\n\nThe element that got deactivated (and will be freed later) will\nremain reachable in the set data structure, this can result in\na crash when such an element is retrieved during lookup (stale\npointer).\n\nAdd a check that the fully matching key does in fact map to the element\nthat we have marked as inactive in the deactivation step.\nIf not, we need to continue searching.\n\nAdd a bug/warn trap at the end of the function as well, the remove\nfunction must not ever be called with an invisible/unreachable/non-existent\nelement.\n\nv2: avoid uneeded temporary variable (Stefano)",
"id": "GHSA-6vh7-f36j-r556",
"modified": "2024-07-03T18:36:47Z",
"published": "2024-04-25T06:30:35Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-26924"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/14b001ba221136c15f894577253e8db535b99487"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3cfc9ec039af60dbd8965ae085b2c2ccdcfbe1cc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/41d8fdf3afaff312e17466e4ab732937738d5644"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7a1679e2d9bfa3b5f8755c2c7113e54b7d42bd46"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e3b887a9c11caf8357a821260e095f2a694a34f2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ebf7c9746f073035ee26209e38c3a1170f7b349a"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/4EZ6PJW7VOZ224TD7N4JZNU6KV32ZJ53"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/DAMSOZXJEPUOXW33WZYWCVAY7Z5S7OOY"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/GCBZZEC7L7KTWWAS2NLJK6SO3IZIL4WW"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}