linux-cve-announce - CVE-2024-57929: dm array: fix releasing a faulty array block twice in dm_array_cursor

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Message-ID: <2025011945-CVE-2024-57929-2b82@gregkh>
Date: Sun, 19 Jan 2025 12:53:00 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-57929: dm array: fix releasing a faulty array block twice in dm_array_cursor_end

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

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

dm array: fix releasing a faulty array block twice in dm_array_cursor_end

When dm_bm_read_lock() fails due to locking or checksum errors, it
releases the faulty block implicitly while leaving an invalid output
pointer behind. The caller of dm_bm_read_lock() should not operate on
this invalid dm_block pointer, or it will lead to undefined result.
For example, the dm_array_cursor incorrectly caches the invalid pointer
on reading a faulty array block, causing a double release in
dm_array_cursor_end(), then hitting the BUG_ON in dm-bufio cache_put().

Reproduce steps:

1. initialize a cache device

dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
dmsetup create cdata --table "0 65536 linear /dev/sdc 8192"
dmsetup create corig --table "0 524288 linear /dev/sdc $262144"
dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1
dmsetup create cache --table "0 524288 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"

2. wipe the second array block offline

dmsteup remove cache cmeta cdata corig
mapping_root=$(dd if=/dev/sdc bs=1c count=8 skip=192 \
2>/dev/null | hexdump -e '1/8 "%u\n"')
ablock=$(dd if=/dev/sdc bs=1c count=8 skip=$((4096*mapping_root+2056)) \
2>/dev/null | hexdump -e '1/8 "%u\n"')
dd if=/dev/zero of=/dev/sdc bs=4k count=1 seek=$ablock

3. try reopen the cache device

dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
dmsetup create cdata --table "0 65536 linear /dev/sdc 8192"
dmsetup create corig --table "0 524288 linear /dev/sdc $262144"
dmsetup create cache --table "0 524288 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"

Kernel logs:

(snip)
device-mapper: array: array_block_check failed: blocknr 0 != wanted 10
device-mapper: block manager: array validator check failed for block 10
device-mapper: array: get_ablock failed
device-mapper: cache metadata: dm_array_cursor_next for mapping failed
------------[ cut here ]------------
kernel BUG at drivers/md/dm-bufio.c:638!

Fix by setting the cached block pointer to NULL on errors.

In addition to the reproducer described above, this fix can be
verified using the "array_cursor/damaged" test in dm-unit:
  dm-unit run /pdata/array_cursor/damaged --kernel-dir <KERNEL_DIR>

The Linux kernel CVE team has assigned CVE-2024-57929 to this issue.


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

	Issue introduced in 4.9 with commit fdd1315aa5f022fe6574efdc2d9535f75a0ee255 and fixed in 6.1.125 with commit e477021d252c007f0c6d45b5d13d341efed03979
	Issue introduced in 4.9 with commit fdd1315aa5f022fe6574efdc2d9535f75a0ee255 and fixed in 6.6.72 with commit 6002bec5354f86d1a2df21468f68e3ec03ede9da
	Issue introduced in 4.9 with commit fdd1315aa5f022fe6574efdc2d9535f75a0ee255 and fixed in 6.12.10 with commit 017c4470bff53585370028fec9341247bad358ff
	Issue introduced in 4.9 with commit fdd1315aa5f022fe6574efdc2d9535f75a0ee255 and fixed in 6.13-rc7 with commit f2893c0804d86230ffb8f1c8703fdbb18648abc8

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-2024-57929
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:
	drivers/md/persistent-data/dm-array.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/e477021d252c007f0c6d45b5d13d341efed03979
	https://git.kernel.org/stable/c/6002bec5354f86d1a2df21468f68e3ec03ede9da
	https://git.kernel.org/stable/c/017c4470bff53585370028fec9341247bad358ff
	https://git.kernel.org/stable/c/f2893c0804d86230ffb8f1c8703fdbb18648abc8