vulnerability

Red Hat: CVE-2024-41012: kernel: filelock: Remove locks reliably when fcntl/close race is detected (Multiple Advisories)

Severity
5
CVSS
(AV:L/AC:L/Au:S/C:N/I:N/A:C)
Published
Jul 23, 2024
Added
Sep 25, 2024
Modified
Jul 9, 2025

Description

In the Linux kernel, the following vulnerability has been resolved:

filelock: Remove locks reliably when fcntl/close race is detected

When fcntl_setlk() races with close(), it removes the created lock with
do_lock_file_wait().
However, LSMs can allow the first do_lock_file_wait() that created the lock
while denying the second do_lock_file_wait() that tries to remove the lock.
Separately, posix_lock_file() could also fail to
remove a lock due to GFP_KERNEL allocation failure (when splitting a range
in the middle).

After the bug has been triggered, use-after-free reads will occur in
lock_get_status() when userspace reads /proc/locks. This can likely be used
to read arbitrary kernel memory, but can't corrupt kernel memory.

Fix it by calling locks_remove_posix() instead, which is designed to
reliably get rid of POSIX locks associated with the given file and
files_struct and is also used by filp_flush().

Solution(s)

no-fix-redhat-rpm-packageredhat-upgrade-kernelredhat-upgrade-kernel-rt
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