CVE-2026-68411: wifi: mac80211_hwsim: clamp virtio RX length before skb_put

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

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

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

wifi: mac80211_hwsim: clamp virtio RX length before skb_put

hwsim_virtio_rx_work() passes the virtqueue used-ring length reported by
the device straight to skb_put() on a fixed-size receive skb. A backend
reporting a length larger than the skb tailroom drives skb_put() past the
buffer end and hits skb_over_panic() -- a host-triggerable guest panic
(denial of service).

Clamp the length to the skb's available room before skb_put(). A
conforming device never reports more than the posted buffer size, so valid
frames are unaffected; a truncated over-report then fails the
length/header checks in hwsim_virtio_handle_cmd() and is dropped, so
truncating rather than dropping here cannot be turned into a parsing
problem.

The Linux kernel CVE team has assigned CVE-2026-68411 to this issue.


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

	Issue introduced in 5.7 with commit 5d44fe7c9808c56e136e59147bd932f5491520f1 and fixed in 6.6.148 with commit 82c5a30a66e2a7337d99476c67d6fc1a99c4250e
	Issue introduced in 5.7 with commit 5d44fe7c9808c56e136e59147bd932f5491520f1 and fixed in 6.12.101 with commit fade308845c89f784da8a6780c1e77258488f1b6
	Issue introduced in 5.7 with commit 5d44fe7c9808c56e136e59147bd932f5491520f1 and fixed in 6.18.42 with commit 6dc76371a9a360c29de00df5b11563102d9d675a
	Issue introduced in 5.7 with commit 5d44fe7c9808c56e136e59147bd932f5491520f1 and fixed in 7.1.6 with commit 99dc05c75acc3c8cde8d89c5371f4b569de5ac62
	Issue introduced in 5.7 with commit 5d44fe7c9808c56e136e59147bd932f5491520f1 and fixed in 7.2-rc4 with commit 10a2b430f8f06ae14b9590b6f6faa6b588ef0654

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-2026-68411
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/virtual/mac80211_hwsim_main.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/82c5a30a66e2a7337d99476c67d6fc1a99c4250e
	https://git.kernel.org/stable/c/fade308845c89f784da8a6780c1e77258488f1b6
	https://git.kernel.org/stable/c/6dc76371a9a360c29de00df5b11563102d9d675a
	https://git.kernel.org/stable/c/99dc05c75acc3c8cde8d89c5371f4b569de5ac62
	https://git.kernel.org/stable/c/10a2b430f8f06ae14b9590b6f6faa6b588ef0654