Subject: CVE-2024-46801: libfs: fix get_stashed_dentry()

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

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

libfs: fix get_stashed_dentry()

get_stashed_dentry() tries to optimistically retrieve a stashed dentry
from a provided location.  It needs to ensure to hold rcu lock before it
dereference the stashed location to prevent UAF issues.  Use
rcu_dereference() instead of READ_ONCE() it's effectively equivalent
with some lockdep bells and whistles and it communicates clearly that
this expects rcu protection.

The Linux kernel CVE team has assigned CVE-2024-46801 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 6.9 with commit 07fd7c329839 and fixed in 6.10.10 with commit 03e2a1209a83
	Issue introduced in 6.9 with commit 07fd7c329839 and fixed in 6.11 with commit 4e32c25b58b9

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-46801
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	fs/libfs.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/03e2a1209a83a380df34a72f7d6d1bc6c74132c7
	https://git.kernel.org/stable/c/4e32c25b58b945f976435bbe51f39b32d714052e