CVE-2023-52699

/// Technical 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).

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References