CVE-2026-53153— mm/list_lru: drain before clearing xarray entry on reparent

mm/list_lru: drain before clearing xarray entry on reparent

In the Linux kernel, the following vulnerability has been resolved: mm/list_lru: drain before clearing xarray entry on reparent memcg_reparent_list_lrus() clears the dying memcg's xarray entry with xas_store(&xas, NULL) before reparenting its per-node lists into the parent. This opens a window where a concurrent list_lru_del() arriving for the dying memcg sees xa_load() == NULL, walks to the parent in lock_list_lru_of_memcg(), takes the parent's per-node lock, and calls list_del_init() on an item still physically linked on the dying memcg's list. If another in-flight thread holds the dying memcg's per-node lock at the same moment (another list_lru_del, or a list_lru_walk_one running an isolate callback), both threads modify ->next/->prev pointers on the same physical list under different locks. Adjacent items can corrupt each other's links. Fix it by reversing the order: reparent each per-node list and mark the child's list lru dead and then clear the xarray entry. Any concurrent list_lru op that finds the still-set xarray entry either takes the dying memcg's per-node lock (synchronizing with the drain) or sees LONG_MIN and walks to the parent, where the items now live.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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Linux 安全漏洞

Linux kernel是美国Linux基金会开源的操作系统Linux所使用的内核。 Linux kernel 6.13版本存在安全漏洞，该漏洞源于mm/list_lru.c中在清除xarray条目前未排空列表，可能导致并发操作下链表指针被破坏。

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