CVE-2024-43892memcg: protect concurrent access to mem_cgroup_idr

Description

In the Linux kernel, the following vulnerability has been resolved: memcg: protect concurrent access to mem_cgroup_idr Commit 73f576c04b94 ("mm: memcontrol: fix cgroup creation failure after many small jobs") decoupled the memcg IDs from the CSS ID space to fix the cgroup creation failures. It introduced IDR to maintain the memcg ID space. The IDR depends on external synchronization mechanisms for modifications. For the mem_cgroup_idr, the idr_alloc() and idr_replace() happen within css callback and thus are protected through cgroup_mutex from concurrent modifications. However idr_remove() for mem_cgroup_idr was not protected against concurrency and can be run concurrently for different memcgs when they hit their refcnt to zero. Fix that. We have been seeing list_lru based kernel crashes at a low frequency in our fleet for a long time. These crashes were in different part of list_lru code including list_lru_add(), list_lru_del() and reparenting code. Upon further inspection, it looked like for a given object (dentry and inode), the super_block's list_lru didn't have list_lru_one for the memcg of that object. The initial suspicions were either the object is not allocated through kmem_cache_alloc_lru() or somehow memcg_list_lru_alloc() failed to allocate list_lru_one() for a memcg but returned success. No evidence were found for these cases. Looking more deeply, we started seeing situations where valid memcg's id is not present in mem_cgroup_idr and in some cases multiple valid memcgs have same id and mem_cgroup_idr is pointing to one of them. So, the most reasonable explanation is that these situations can happen due to race between multiple idr_remove() calls or race between idr_alloc()/idr_replace() and idr_remove(). These races are causing multiple memcgs to acquire the same ID and then offlining of one of them would cleanup list_lrus on the system for all of them. Later access from other memcgs to the list_lru cause crashes due to missing list_lru_one.

Timeline

Scores

EPSS (exploitation in 30 days)

0.25% · top 84% of all CVEs (14 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.

Affected products

• Linux · Linux

  • affected 73f576c04b9410ed19660f74f97521bee6e1c546 – < 912736a0435ef40e6a4ae78197ccb5553cb80b05
  • affected 73f576c04b9410ed19660f74f97521bee6e1c546 – < e6cc9ff2ac0b5df9f25eb790934c3104f6710278
  • affected 73f576c04b9410ed19660f74f97521bee6e1c546 – < 56fd70f4aa8b82199dbe7e99366b1fd7a04d86fb
  • affected 73f576c04b9410ed19660f74f97521bee6e1c546 – < 37a060b64ae83b76600d187d76591ce488ab836b
  • affected 73f576c04b9410ed19660f74f97521bee6e1c546 – < 51c0b1bb7541f8893ec1accba59eb04361a70946
  • affected 73f576c04b9410ed19660f74f97521bee6e1c546 – < 9972605a238339b85bd16b084eed5f18414d22db
  • affected 8627c7750a66a46d56d3564e1e881aa53764497c
  • affected db70cd18d3da727a3a59694de428a9e41c620de7
  • affected 4.4.18 – < 4.5
  • affected 4.6.6 – < 4.7

• Linux · Linux

  • affected 4.7
  • unaffected < 4.7
  • unaffected 5.10.226 – ≤ 5.10.*
  • unaffected 5.15.167 – ≤ 5.15.*
  • unaffected 6.1.110 – ≤ 6.1.*
  • unaffected 6.6.46 – ≤ 6.6.*
  • unaffected 6.10.5 – ≤ 6.10.*
  • unaffected 6.11 – ≤ *

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2024-40542 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2024-43892](https://cveledger.app/badge/CVE-2024-43892.svg)](https://cveledger.app/cve/CVE-2024-43892)

Record last updated 5 Aug 2026, 11:37 UTC.