mm: zswap: fix shrinker NULL crash with cgroup_disable=memory

{
  "id": "4d769bfb89fd8a885f6b3f85102b301b9466c9889f8d3d30bbe3fe5ee7621ece",
  "url": "https://osv.dev/vulnerability/CVE-2024-35846",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "mm: zswap: fix shrinker NULL crash with cgroup_disable=memory",
    "summary": "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",
    "evidence": "osv:CVE-2024-35846",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.8.9",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2024-35846",
      "aliases": [
        "CVE-2024-35846"
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      "affected": [
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                {
                  "fixed": "682886ec69d22363819a83ddddd5d66cb5c791e1"
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          "ranges": [
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              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.8.0"
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                  "fixed": "6.8.9"
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-35846.json"
          }
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      ],
      "modified": "2026-10-28T02:30:24.726331145Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/682886ec69d22363819a83ddddd5d66cb5c791e1",
        "https://git.kernel.org/stable/c/b0fdabc908a7f81d12382c87ca9e46a9c2e14042",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/35xxx/CVE-2024-35846.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-35846",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/35xxx/CVE-2024-35846.json"
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    "related_cves": [
      {
        "value": "CVE-2024-35846",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 490824,
  "published_at": "2024-05-17T14:47:25.503+00:00"
}