linux-cve-announce - CVE-2023-52668: btrfs: zoned: fix lock ordering in btrfs_zone

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Message-ID: <2024051728-CVE-2023-52668-4da2@gregkh>
Date: Fri, 17 May 2024 16:01:29 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2023-52668: btrfs: zoned: fix lock ordering in btrfs_zone_activate()

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

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

btrfs: zoned: fix lock ordering in btrfs_zone_activate()

The btrfs CI reported a lockdep warning as follows by running generic
generic/129.

   WARNING: possible circular locking dependency detected
   6.7.0-rc5+ #1 Not tainted
   ------------------------------------------------------
   kworker/u5:5/793427 is trying to acquire lock:
   ffff88813256d028 (&cache->lock){+.+.}-{2:2}, at: btrfs_zone_finish_one_bg+0x5e/0x130
   but task is already holding lock:
   ffff88810a23a318 (&fs_info->zone_active_bgs_lock){+.+.}-{2:2}, at: btrfs_zone_finish_one_bg+0x34/0x130
   which lock already depends on the new lock.

   the existing dependency chain (in reverse order) is:
   -> #1 (&fs_info->zone_active_bgs_lock){+.+.}-{2:2}:
   ...
   -> #0 (&cache->lock){+.+.}-{2:2}:
   ...

This is because we take fs_info->zone_active_bgs_lock after a block_group's
lock in btrfs_zone_activate() while doing the opposite in other places.

Fix the issue by expanding the fs_info->zone_active_bgs_lock's critical
section and taking it before a block_group's lock.

The Linux kernel CVE team has assigned CVE-2023-52668 to this issue.


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

	Issue introduced in 6.6 with commit a7e1ac7bdc5a and fixed in 6.6.15 with commit 6f74989f5909
	Issue introduced in 6.6 with commit a7e1ac7bdc5a and fixed in 6.7.3 with commit 1908e9d01e53
	Issue introduced in 6.6 with commit a7e1ac7bdc5a and fixed in 6.8 with commit b18f3b60b35a

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-2023-52668
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/btrfs/zoned.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/6f74989f5909cdec9b1274641f0fa306b15bb476
	https://git.kernel.org/stable/c/1908e9d01e5395adff68d9d308a0fb15337e6272
	https://git.kernel.org/stable/c/b18f3b60b35a8c01c9a2a0f0d6424c6d73971dc3