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CVE Record

CVE-2024-35846: mm: zswap: fix shrinker NULL crash with cgroup_disable=memory

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

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2024-35846 is a Linux kernel crash bug in zswap. On systems booted with memory cgroups disabled, the zswap shrinker can hit a NULL pointer and crash the kernel. The provided sources support an availability concern, not data theft or privilege escalation.

Executive priority

Treat this as an availability risk for a narrow Linux configuration. Prioritize production hosts matching the affected kernel and boot setting, especially virtualization, appliance, or infrastructure systems where an unexpected kernel crash creates business disruption.

Technical view

When memcg is disabled using cgroup_disable=memory, the zswap shrinker may run with sc->memcg set to NULL. Code paths using memcg_page_state() did not tolerate that NULL value, causing a NULL dereference. Kernel stable commits are referenced as the resolution.

Likely exposure

Exposure appears limited to affected Linux 6.8-era kernels using zswap with memory cgroups disabled at boot. Confirm actual exposure through kernel version, vendor backports, boot parameters, and zswap status.

Exploitation context

The CVE is not listed as CISA KEV in the provided bundle. Sources describe observed crashes and bug tracker reports, but do not document active exploitation or a weaponized attack path.

Researcher notes

The source evidence is specific: zswap shrinker behavior with memcg disabled. The bundle provides no CVSS, CWE, exploit status, or broad affected-product mapping. Avoid extrapolating beyond Linux kernels and configurations matching the described condition.

Mitigation direction

  • Apply a vendor kernel update containing the referenced stable fixes.
  • Confirm whether your distribution backported the fix into its supported kernel.
  • Review boot parameters for cgroup_disable=memory on affected hosts.
  • If unpatched, consult vendor guidance before changing zswap or cgroup settings.
  • Prioritize systems where kernel crashes would affect production availability.

Validation and detection

  • Inventory Linux hosts running affected 6.8-series kernels.
  • Check boot configuration for cgroup_disable=memory.
  • Confirm whether zswap is enabled on those hosts.
  • Review kernel logs for zswap, shrinker, memcg_page_state, or NULL dereference crashes.
  • Verify fixed kernel build provenance against vendor advisories or stable commit references.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2024-35846 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
2ADP providers
3Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxb5ba474f3f518701249598b35c581b92a3c95b48, b5ba474f3f518701249598b35c581b92a3c95b48unaffected
LinuxLinux6.8, 0, 6.8.9, 6.9affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.