CVE-2026-98698: wifi: mac80211: handle empty FILS association request payload

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

wifi: mac80211: handle empty FILS association request payload

fils_encrypt_assoc_req() accepts a (Re)Association Request frame whose
last element is the FILS Session element.  crypt_len is then zero and
aes_siv_encrypt() is called with an empty plaintext.

kmemdup() returns ZERO_SIZE_PTR for a zero-length allocation, so the
unconditional sg_init_one() puts an invalid page into the scatterlist.
With CONFIG_DEBUG_SG this triggers a kernel BUG in sg_set_buf();
without the debug check the bogus page is handed to the crypto backend.

AES-SIV is defined for empty plaintext and the S2V result is then the
complete output, so handle this case before the CTR step, which has
nothing to encrypt.

The Linux kernel CVE team has assigned CVE-2026-98698 to this issue.


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

	Issue introduced in 4.10 with commit 39404feee691a2dc524a629ed6eb5cfe5d8898d1 and fixed in 6.12.113 with commit 2f5b62f6534d336a62fdb9e88b186dd70b4323ef
	Issue introduced in 4.10 with commit 39404feee691a2dc524a629ed6eb5cfe5d8898d1 and fixed in 6.18.56 with commit 452f1c9b76f7a122bbc4630b9691bda4809677c4
	Issue introduced in 4.10 with commit 39404feee691a2dc524a629ed6eb5cfe5d8898d1 and fixed in 7.2.10 with commit 20f939b0c151d1d28e6b62a76b2454fa6fe877f2
	Issue introduced in 4.10 with commit 39404feee691a2dc524a629ed6eb5cfe5d8898d1 and fixed in 7.3-rc6 with commit 5bfd4b0b40b79781d900cb2f7da0685070f53c67

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-2026-98698
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:
	net/mac80211/fils_aead.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/2f5b62f6534d336a62fdb9e88b186dd70b4323ef
	https://git.kernel.org/stable/c/452f1c9b76f7a122bbc4630b9691bda4809677c4
	https://git.kernel.org/stable/c/20f939b0c151d1d28e6b62a76b2454fa6fe877f2
	https://git.kernel.org/stable/c/5bfd4b0b40b79781d900cb2f7da0685070f53c67