linux-cve-announce - CVE-2024-50014: ext4: fix access to uninitialised lock in fc replay path

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Message-ID: <2024102110-CVE-2024-50014-d684@gregkh>
Date: Mon, 21 Oct 2024 20:54:18 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-50014: ext4: fix access to uninitialised lock in fc replay path

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

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

ext4: fix access to uninitialised lock in fc replay path

The following kernel trace can be triggered with fstest generic/629 when
executed against a filesystem with fast-commit feature enabled:

INFO: trying to register non-static key.
The code is fine but needs lockdep annotation, or maybe
you didn't initialize this object before use?
turning off the locking correctness validator.
CPU: 0 PID: 866 Comm: mount Not tainted 6.10.0+ #11
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-3-gd478f380-prebuilt.qemu.org 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x66/0x90
 register_lock_class+0x759/0x7d0
 __lock_acquire+0x85/0x2630
 ? __find_get_block+0xb4/0x380
 lock_acquire+0xd1/0x2d0
 ? __ext4_journal_get_write_access+0xd5/0x160
 _raw_spin_lock+0x33/0x40
 ? __ext4_journal_get_write_access+0xd5/0x160
 __ext4_journal_get_write_access+0xd5/0x160
 ext4_reserve_inode_write+0x61/0xb0
 __ext4_mark_inode_dirty+0x79/0x270
 ? ext4_ext_replay_set_iblocks+0x2f8/0x450
 ext4_ext_replay_set_iblocks+0x330/0x450
 ext4_fc_replay+0x14c8/0x1540
 ? jread+0x88/0x2e0
 ? rcu_is_watching+0x11/0x40
 do_one_pass+0x447/0xd00
 jbd2_journal_recover+0x139/0x1b0
 jbd2_journal_load+0x96/0x390
 ext4_load_and_init_journal+0x253/0xd40
 ext4_fill_super+0x2cc6/0x3180
...

In the replay path there's an attempt to lock sbi->s_bdev_wb_lock in
function ext4_check_bdev_write_error().  Unfortunately, at this point this
spinlock has not been initialized yet.  Moving it's initialization to an
earlier point in __ext4_fill_super() fixes this splat.

The Linux kernel CVE team has assigned CVE-2024-50014 to this issue.

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

	Fixed in 6.10.14 with commit d157fc20ca52
	Fixed in 6.11.3 with commit b002031d585a
	Fixed in 6.12-rc1 with commit 23dfdb56581a

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-2024-50014
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/ext4/super.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/d157fc20ca5239fd56965a5a8aa1a0e25919891a
	https://git.kernel.org/stable/c/b002031d585a14eed511117dda8c6452a804d508
	https://git.kernel.org/stable/c/23dfdb56581ad92a9967bcd720c8c23356af74c1