linux-cve-announce - CVE-2022-49464: erofs: fix buffer copy overflow of ztailpacking feature

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Message-ID: <2025022601-CVE-2022-49464-7407@gregkh>
Date: Wed, 26 Feb 2025 03:12:18 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2022-49464: erofs: fix buffer copy overflow of ztailpacking feature

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

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

erofs: fix buffer copy overflow of ztailpacking feature

I got some KASAN report as below:

[   46.959738] ==================================================================
[   46.960430] BUG: KASAN: use-after-free in z_erofs_shifted_transform+0x2bd/0x370
[   46.960430] Read of size 4074 at addr ffff8880300c2f8e by task fssum/188
...
[   46.960430] Call Trace:
[   46.960430]  <TASK>
[   46.960430]  dump_stack_lvl+0x41/0x5e
[   46.960430]  print_report.cold+0xb2/0x6b7
[   46.960430]  ? z_erofs_shifted_transform+0x2bd/0x370
[   46.960430]  kasan_report+0x8a/0x140
[   46.960430]  ? z_erofs_shifted_transform+0x2bd/0x370
[   46.960430]  kasan_check_range+0x14d/0x1d0
[   46.960430]  memcpy+0x20/0x60
[   46.960430]  z_erofs_shifted_transform+0x2bd/0x370
[   46.960430]  z_erofs_decompress_pcluster+0xaae/0x1080

The root cause is that the tail pcluster won't be a complete filesystem
block anymore. So if ztailpacking is used, the second part of an
uncompressed tail pcluster may not be ``rq->pageofs_out``.

The Linux kernel CVE team has assigned CVE-2022-49464 to this issue.


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

	Issue introduced in 5.17 with commit ab749badf9f41f32509cd103391b81ea7e684b76 and fixed in 5.17.14 with commit 4d53a625f29074e7b8236c2c0e0922edb7608df9
	Issue introduced in 5.17 with commit ab749badf9f41f32509cd103391b81ea7e684b76 and fixed in 5.18.3 with commit 6b59e1907f58cf877c563dcf013159eb9f994b64
	Issue introduced in 5.17 with commit ab749badf9f41f32509cd103391b81ea7e684b76 and fixed in 5.19 with commit dcbe6803fffd387f72b48c2373b5f5ed12a5804b

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-2022-49464
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/erofs/decompressor.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/4d53a625f29074e7b8236c2c0e0922edb7608df9
	https://git.kernel.org/stable/c/6b59e1907f58cf877c563dcf013159eb9f994b64
	https://git.kernel.org/stable/c/dcbe6803fffd387f72b48c2373b5f5ed12a5804b