ghsa-657p-cp5v-hvxv
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
mm: zswap: fix shrinker NULL crash with cgroup_disable=memory
Christian reports a NULL deref in zswap that he bisected down to the zswap shrinker. The issue also cropped up in the bug trackers of libguestfs [1] and the Red Hat bugzilla [2].
The problem is that when memcg is disabled with the boot time flag, the zswap shrinker might get called with sc->memcg == NULL. This is okay in many places, like the lruvec operations. But it crashes in memcg_page_state() - which is only used due to the non-node accounting of cgroup's the zswap memory to begin with.
Nhat spotted that the memcg can be NULL in the memcg-disabled case, and I was then able to reproduce the crash locally as well.
[1] https://github.com/libguestfs/libguestfs/issues/139 [2] https://bugzilla.redhat.com/show_bug.cgi?id=2275252
{
"affected": [],
"aliases": [
"CVE-2024-35846"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-17T15:15:21Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: zswap: fix shrinker NULL crash with cgroup_disable=memory\n\nChristian reports a NULL deref in zswap that he bisected down to the zswap\nshrinker. The issue also cropped up in the bug trackers of libguestfs [1]\nand the Red Hat bugzilla [2].\n\nThe problem is that when memcg is disabled with the boot time flag, the\nzswap shrinker might get called with sc-\u003ememcg == NULL. This is okay in\nmany places, like the lruvec operations. But it crashes in\nmemcg_page_state() - which is only used due to the non-node accounting of\ncgroup\u0027s the zswap memory to begin with.\n\nNhat spotted that the memcg can be NULL in the memcg-disabled case, and I\nwas then able to reproduce the crash locally as well.\n\n[1] https://github.com/libguestfs/libguestfs/issues/139\n[2] https://bugzilla.redhat.com/show_bug.cgi?id=2275252",
"id": "GHSA-657p-cp5v-hvxv",
"modified": "2024-05-17T15:31:12Z",
"published": "2024-05-17T15:31:12Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-35846"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/682886ec69d22363819a83ddddd5d66cb5c791e1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b0fdabc908a7f81d12382c87ca9e46a9c2e14042"
}
],
"schema_version": "1.4.0",
"severity": []
}