CVE-2023-52699: sysv: don't call sb_bread() with pointers_lock held

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.0% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-05-19 · updated 2026-10-15
Weakness: CWE-667

Description

In the Linux kernel, the following vulnerability has been resolved: sysv: don't call sb_bread() with pointers_lock held syzbot is reporting sleep in atomic context in SysV filesystem [1], for sb_bread() is called with rw_spinlock held. A "write_lock(&pointers_lock) => read_lock(&pointers_lock) deadlock" bug and a "sb_bread() with write_lock(&pointers_lock)" bug were introduced by "Replace BKL for chain locking with sysvfs-private rwlock" in Linux 2.5.12. Then, "[PATCH] err1-40: sysvfs locking fix" in Linux 2.6.8 fixed the former bug by moving pointers_lock lock to the callers, but instead introduced a "sb_bread() with read_lock(&pointers_lock)" bug (which made this problem easier to hit). Al Viro suggested that why not to do like get_branch()/get_block()/ find_shared() in Minix filesystem does. And doing like that is almost a revert of "[PATCH] err1-40: sysvfs locking fix" except that get_branch() from with find_shared() is called without write_lock(&pointers_lock).

Affected products

Debian Linux: 10.0
Linux kernel: before 4.19.312; from 4.20 before 5.4.274; from 5.5 before 5.10.215; from 5.11 before 5.15.155; from 5.16 before 6.1.86; from 6.2 before 6.6.27 — fixed in 4.19.312, 5.10.215, 5.15.155, 5.4.274, 6.1.86, 6.6.27

How to fix

Upgrade to a fixed version: Linux kernel 4.19.312, 5.10.215, 5.15.155, 5.4.274. Check the vendor advisory for mitigations.

References

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