ghsa-657p-cp5v-hvxv
Vulnerability from github
Published
2024-05-17 15:31
Modified
2024-05-17 15:31
Details

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

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{
  "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": []
}


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