CVE-2026-74409: wifi: rtw89: add bounds check on firmware mac_id in link lookup

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

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

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

wifi: rtw89: add bounds check on firmware mac_id in link lookup

The mac_id field in RX descriptors is 8 bits wide (0-255), but
assoc_link_on_macid[] has only RTW89_MAX_MAC_ID_NUM (128) entries.
While the driver currently assigns mac_id values below 128, the
descriptor value comes from firmware and is not validated before use
as an array index. Add a defensive bounds check in
rtw89_assoc_link_rcu_dereference() to guard against out-of-range
firmware values.

The Linux kernel CVE team has assigned CVE-2026-74409 to this issue.


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

	Issue introduced in 6.14 with commit 144c6cd24b3556e6e7a14271cee57a42ebf97450 and fixed in 6.18.40 with commit ad445de67359f24088d4305c05fbd7e34c4e35e3
	Issue introduced in 6.14 with commit 144c6cd24b3556e6e7a14271cee57a42ebf97450 and fixed in 7.1.5 with commit 920101305e7601a33b9e01019f4ca526af2526ae
	Issue introduced in 6.14 with commit 144c6cd24b3556e6e7a14271cee57a42ebf97450 and fixed in 7.2-rc1 with commit 6d88244bb129755acca696f9227200f4a2d106a6

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-2026-74409
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/net/wireless/realtek/rtw89/core.h


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/ad445de67359f24088d4305c05fbd7e34c4e35e3
	https://git.kernel.org/stable/c/920101305e7601a33b9e01019f4ca526af2526ae
	https://git.kernel.org/stable/c/6d88244bb129755acca696f9227200f4a2d106a6