CVE-2023-53608: nilfs2: fix potential UAF of struct nilfs_sc_info in nilfs_segctor_thread()

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-10-04 · updated 2026-08-04
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix potential UAF of struct nilfs_sc_info in nilfs_segctor_thread() The finalization of nilfs_segctor_thread() can race with nilfs_segctor_kill_thread() which terminates that thread, potentially causing a use-after-free BUG as KASAN detected. At the end of nilfs_segctor_thread(), it assigns NULL to "sc_task" member of "struct nilfs_sc_info" to indicate the thread has finished, and then notifies nilfs_segctor_kill_thread() of this using waitqueue "sc_wait_task" on the struct nilfs_sc_info. However, here, immediately after the NULL assignment to "sc_task", it is possible that nilfs_segctor_kill_thread() will detect it and return to continue the deallocation, freeing the nilfs_sc_info structure before the thread does the notification. This fixes the issue by protecting the NULL assignment to "sc_task" and its notification, with spinlock "sc_state_lock" of the struct nilfs_sc_info. Since nilfs_segctor_kill_thread() does a final check to see if "sc_task" is NULL with "sc_state_lock" locked, this can eliminate the race.

Affected products

Linux kernel: from 2.6.30 before 4.14.313; from 4.15 before 4.19.281; from 4.20 before 5.4.241; from 5.5 before 5.10.178; from 5.11 before 5.15.107; from 5.16 before 6.1.24 — fixed in 4.14.313, 4.19.281, 5.10.178, 5.15.107, 5.4.241, 6.1.24

How to fix

Upgrade to a fixed version: Linux kernel 4.14.313, 4.19.281, 5.10.178, 5.15.107. Check the vendor advisory for mitigations.

References

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