Subject: CVE-2024-47705: block: fix potential invalid pointer dereference in blk_add_partition

From: Greg Kroah-Hartman <[email-masked]>

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

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

block: fix potential invalid pointer dereference in blk_add_partition

The blk_add_partition() function initially used a single if-condition
(IS_ERR(part)) to check for errors when adding a partition. This was
modified to handle the specific case of -ENXIO separately, allowing the
function to proceed without logging the error in this case. However,
this change unintentionally left a path where md_autodetect_dev()
could be called without confirming that part is a valid pointer.

This commit separates the error handling logic by splitting the
initial if-condition, improving code readability and handling specific
error scenarios explicitly. The function now distinguishes the general
error case from -ENXIO without altering the existing behavior of
md_autodetect_dev() calls.

The Linux kernel CVE team has assigned CVE-2024-47705 to this issue.

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

	Issue introduced in 5.5 with commit b72053072c0b and fixed in 5.10.227 with commit 4bc4272e2506
	Issue introduced in 5.5 with commit b72053072c0b and fixed in 5.15.168 with commit cc4d21d9492d
	Issue introduced in 5.5 with commit b72053072c0b and fixed in 6.1.113 with commit 64cf2a39202c
	Issue introduced in 5.5 with commit b72053072c0b and fixed in 6.6.54 with commit 80f5bfbb80ea
	Issue introduced in 5.5 with commit b72053072c0b and fixed in 6.10.13 with commit 652039ba477c
	Issue introduced in 5.5 with commit b72053072c0b and fixed in 6.11.2 with commit afe53ea9b378
	Issue introduced in 5.5 with commit b72053072c0b and fixed in 6.12-rc1 with commit 26e197b7f924

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-2024-47705
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:
	block/partitions/core.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/4bc4272e2506941c3f3d4fb8b0c659ee814dcf6f
	https://git.kernel.org/stable/c/cc4d21d9492db4e534d3e01253cf885c90dd2a8b
	https://git.kernel.org/stable/c/64cf2a39202ca2d9df5ee70eb310b6141ce2b8ed
	https://git.kernel.org/stable/c/80f5bfbb80ea1615290dbc24f49d3d8c86db58fe
	https://git.kernel.org/stable/c/652039ba477c9a4ab43740cf2cb0d068d53508c2
	https://git.kernel.org/stable/c/afe53ea9b378c376101d99d216f13b6256f75189
	https://git.kernel.org/stable/c/26e197b7f9240a4ac301dd0ad520c0c697c2ea7d