linux-cve-announce - CVE-2023-53608: nilfs2: fix potential UAF of struct nilfs_sc_info in nilfs_segctor

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Message-ID: <2025100432-CVE-2023-53608-ccb6@gregkh>
Date: Sat,  4 Oct 2025 17:52:02 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53608: nilfs2: fix potential UAF of struct nilfs_sc_info in nilfs_segctor_thread()

From: Greg Kroah-Hartman <gregkh@...nel.org>

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.

The Linux kernel CVE team has assigned CVE-2023-53608 to this issue.

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

	Fixed in 4.14.313 with commit 034cce77d52ba013ce62b4f5258c29907eb1ada5
	Fixed in 4.19.281 with commit 0dbf0e64b91ee8fcb278aea93eb06fc7d56ecbcc
	Fixed in 5.4.241 with commit 613bf23c070d11c525268f2945aa594704a9b764
	Fixed in 5.10.178 with commit f32297dba338dc06d62286dedb3cdbd5175b1719
	Fixed in 5.15.107 with commit 92684e02654c91a61a0b0561433b710bcece19fe
	Fixed in 6.1.24 with commit bae009a2f1b7c2011d2e92d8c84868d315c0b97e
	Fixed in 6.2.11 with commit b4d80bd6370b81a1725b6b8f7894802c23a14e9f
	Fixed in 6.3 with commit 6be49d100c22ffea3287a4b19d7639d259888e33

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-2023-53608
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/nilfs2/segment.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/034cce77d52ba013ce62b4f5258c29907eb1ada5
	https://git.kernel.org/stable/c/0dbf0e64b91ee8fcb278aea93eb06fc7d56ecbcc
	https://git.kernel.org/stable/c/613bf23c070d11c525268f2945aa594704a9b764
	https://git.kernel.org/stable/c/f32297dba338dc06d62286dedb3cdbd5175b1719
	https://git.kernel.org/stable/c/92684e02654c91a61a0b0561433b710bcece19fe
	https://git.kernel.org/stable/c/bae009a2f1b7c2011d2e92d8c84868d315c0b97e
	https://git.kernel.org/stable/c/b4d80bd6370b81a1725b6b8f7894802c23a14e9f
	https://git.kernel.org/stable/c/6be49d100c22ffea3287a4b19d7639d259888e33