CVE-2026-72022: llc: fix SAP refcount leak in llc_ui_autobind()

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

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

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

llc: fix SAP refcount leak in llc_ui_autobind()

llc_ui_autobind() opens a SAP after choosing a dynamic LSAP.
llc_sap_open() returns a reference owned by the caller, and
llc_sap_add_socket() takes a second reference for the socket's
membership in the SAP hash tables.

llc_ui_bind() drops the caller's reference after adding the socket,
but llc_ui_autobind() keeps it. When the socket is closed,
llc_sap_remove_socket() releases only the socket reference, leaving
the SAP on llc_sap_list with sk_count == 0.

This is user-visible because repeated autobind and close cycles can consume
all dynamic SAP values and make later autobinds fail with -EUSERS.

Drop the caller's reference after a successful autobind, matching
llc_ui_bind()'s ownership model.

The Linux kernel CVE team has assigned CVE-2026-72022 to this issue.


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

	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 5.10.261 with commit 79dc4b508e3f2649390a1f745f7657813e5938ec
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 5.15.212 with commit a2f9fa31ae021ef1fdcaf3ab17bd49f9223dd6a4
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.1.178 with commit b589a965184dde49c43b8caf5bcc65715a7b4ef2
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.6.145 with commit c7881b6088276601beaccb7440b8d56eab0d65ae
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.12.97 with commit b2fc9955ddc7c4ca03be44b995193bd6486c62e1
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.18.40 with commit 61a7ff4a62003b55a15022567486741b3bd83914
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 7.1.5 with commit 21a537606fe35be2b85971a5fd35c0023b6ef98f
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 7.2-rc3 with commit 660667cd406648bbaffbd5c0d897c2263a852f11

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-2026-72022
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/llc/af_llc.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/79dc4b508e3f2649390a1f745f7657813e5938ec
	https://git.kernel.org/stable/c/a2f9fa31ae021ef1fdcaf3ab17bd49f9223dd6a4
	https://git.kernel.org/stable/c/b589a965184dde49c43b8caf5bcc65715a7b4ef2
	https://git.kernel.org/stable/c/c7881b6088276601beaccb7440b8d56eab0d65ae
	https://git.kernel.org/stable/c/b2fc9955ddc7c4ca03be44b995193bd6486c62e1
	https://git.kernel.org/stable/c/61a7ff4a62003b55a15022567486741b3bd83914
	https://git.kernel.org/stable/c/21a537606fe35be2b85971a5fd35c0023b6ef98f
	https://git.kernel.org/stable/c/660667cd406648bbaffbd5c0d897c2263a852f11