{"id":"AZL-59919","summary":"CVE-2025-21919 affecting package kernel for versions less than 6.6.85.1-2","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/fair: Fix potential memory corruption in child_cfs_rq_on_list\n\nchild_cfs_rq_on_list attempts to convert a 'prev' pointer to a cfs_rq.\nThis 'prev' pointer can originate from struct rq's leaf_cfs_rq_list,\nmaking the conversion invalid and potentially leading to memory\ncorruption. Depending on the relative positions of leaf_cfs_rq_list and\nthe task group (tg) pointer within the struct, this can cause a memory\nfault or access garbage data.\n\nThe issue arises in list_add_leaf_cfs_rq, where both\ncfs_rq-\u003eleaf_cfs_rq_list and rq-\u003eleaf_cfs_rq_list are added to the same\nleaf list. Also, rq-\u003etmp_alone_branch can be set to rq-\u003eleaf_cfs_rq_list.\n\nThis adds a check `if (prev == &rq-\u003eleaf_cfs_rq_list)` after the main\nconditional in child_cfs_rq_on_list. This ensures that the container_of\noperation will convert a correct cfs_rq struct.\n\nThis check is sufficient because only cfs_rqs on the same CPU are added\nto the list, so verifying the 'prev' pointer against the current rq's list\nhead is enough.\n\nFixes a potential memory corruption issue that due to current struct\nlayout might not be manifesting as a crash but could lead to unpredictable\nbehavior when the layout changes.","modified":"2026-04-01T05:19:52.477529Z","published":"2025-04-01T16:15:22Z","upstream":["CVE-2025-21919"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-21919"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.85.1-2"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-59919.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}