CVE-2026-98320: netfilter: flowtable: hold reference on ct until flow is released

CVE-2026-98320: netfilter: flowtable: hold reference on ct until flow is released

[Greg Kroah-Hartman]

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

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

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

netfilter: flowtable: hold reference on ct until flow is released

nf_ct_put() releases the ct->ext area inmediately, the rcu typesafe
semantics also allow to refer to the wrong conntrack from the flowtable
datapath. Hold reference on ct until flow is released after rcu grace
period.

Add rcu_barrier() on module exit path, to ensure pending flow entries
are release before module goes away.

The Linux kernel CVE team has assigned CVE-2026-98320 to this issue.


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

	Issue introduced in 4.16 with commit 0ff90b6c20340e57616a51ae1a1bf18156d6638a and fixed in 5.10.271 with commit 93ff1594be1aad4da364462dd8db050ebcfda2de
	Issue introduced in 4.16 with commit 0ff90b6c20340e57616a51ae1a1bf18156d6638a and fixed in 5.15.222 with commit eed6997e8dc40593a539fcc722e7ed51b18db86c
	Issue introduced in 4.16 with commit 0ff90b6c20340e57616a51ae1a1bf18156d6638a and fixed in 6.1.189 with commit 61c6688be282277c6e91ab286a7acd0ae8681ac6
	Issue introduced in 4.16 with commit 0ff90b6c20340e57616a51ae1a1bf18156d6638a and fixed in 6.6.158 with commit a43cd2b67b91e943273c913237a7a88c50cdcfbc
	Issue introduced in 4.16 with commit 0ff90b6c20340e57616a51ae1a1bf18156d6638a and fixed in 6.12.112 with commit 8274cdc5f9c57e17ed77fc4ba76212536c840f25
	Issue introduced in 4.16 with commit 0ff90b6c20340e57616a51ae1a1bf18156d6638a and fixed in 6.18.54 with commit 12c1ac230f4ca16e0017b62a963ab75e0b48074f
	Issue introduced in 4.16 with commit 0ff90b6c20340e57616a51ae1a1bf18156d6638a and fixed in 7.2.8 with commit d9e6175a3ee48209ee65f294fc567b4e16b29b74
	Issue introduced in 4.16 with commit 0ff90b6c20340e57616a51ae1a1bf18156d6638a and fixed in 7.3-rc4 with commit e75a9fa1d44bcbd66ea02e8781bcca6ea4076e0d

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-2026-98320
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/netfilter/nf_flow_table_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/93ff1594be1aad4da364462dd8db050ebcfda2de
	https://git.kernel.org/stable/c/eed6997e8dc40593a539fcc722e7ed51b18db86c
	https://git.kernel.org/stable/c/61c6688be282277c6e91ab286a7acd0ae8681ac6
	https://git.kernel.org/stable/c/a43cd2b67b91e943273c913237a7a88c50cdcfbc
	https://git.kernel.org/stable/c/8274cdc5f9c57e17ed77fc4ba76212536c840f25
	https://git.kernel.org/stable/c/12c1ac230f4ca16e0017b62a963ab75e0b48074f
	https://git.kernel.org/stable/c/d9e6175a3ee48209ee65f294fc567b4e16b29b74
	https://git.kernel.org/stable/c/e75a9fa1d44bcbd66ea02e8781bcca6ea4076e0d