linux-cve-announce - CVE-2024-37078: nilfs2: fix potential kernel bug due to lack of writeback flag waiting

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Message-ID: <2024062547-CVE-2024-37078-3aaa@gregkh>
Date: Tue, 25 Jun 2024 16:22:48 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-37078: nilfs2: fix potential kernel bug due to lack of writeback flag waiting

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

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

nilfs2: fix potential kernel bug due to lack of writeback flag waiting

Destructive writes to a block device on which nilfs2 is mounted can cause
a kernel bug in the folio/page writeback start routine or writeback end
routine (__folio_start_writeback in the log below):

 kernel BUG at mm/page-writeback.c:3070!
 Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
 ...
 RIP: 0010:__folio_start_writeback+0xbaa/0x10e0
 Code: 25 ff 0f 00 00 0f 84 18 01 00 00 e8 40 ca c6 ff e9 17 f6 ff ff
  e8 36 ca c6 ff 4c 89 f7 48 c7 c6 80 c0 12 84 e8 e7 b3 0f 00 90 <0f>
  0b e8 1f ca c6 ff 4c 89 f7 48 c7 c6 a0 c6 12 84 e8 d0 b3 0f 00
 ...
 Call Trace:
  <TASK>
  nilfs_segctor_do_construct+0x4654/0x69d0 [nilfs2]
  nilfs_segctor_construct+0x181/0x6b0 [nilfs2]
  nilfs_segctor_thread+0x548/0x11c0 [nilfs2]
  kthread+0x2f0/0x390
  ret_from_fork+0x4b/0x80
  ret_from_fork_asm+0x1a/0x30
  </TASK>

This is because when the log writer starts a writeback for segment summary
blocks or a super root block that use the backing device's page cache, it
does not wait for the ongoing folio/page writeback, resulting in an
inconsistent writeback state.

Fix this issue by waiting for ongoing writebacks when putting
folios/pages on the backing device into writeback state.

The Linux kernel CVE team has assigned CVE-2024-37078 to this issue.


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

	Issue introduced in 2.6.30 with commit 9ff05123e3bf and fixed in 6.1.95 with commit 271dcd977ccd
	Issue introduced in 2.6.30 with commit 9ff05123e3bf and fixed in 6.6.35 with commit 614d397be0cf
	Issue introduced in 2.6.30 with commit 9ff05123e3bf and fixed in 6.9.5 with commit 1f3bff69f121
	Issue introduced in 2.6.30 with commit 9ff05123e3bf and fixed in 6.10-rc3 with commit a4ca369ca221

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-2024-37078
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/271dcd977ccda8c7a26e360425ae7b4db7d2ecc0
	https://git.kernel.org/stable/c/614d397be0cf43412b3f94a0f6460eddced8ce92
	https://git.kernel.org/stable/c/1f3bff69f1214fe03a02bc650d5bbfaa6e65ae7d
	https://git.kernel.org/stable/c/a4ca369ca221bb7e06c725792ac107f0e48e82e7