CVE-2026-72430: net/sched: act_ct: fix nf_connlabels leak on two error paths

CVE-2026-72430: net/sched: act_ct: fix nf_connlabels leak on two error paths

[Greg Kroah-Hartman]

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

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

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

net/sched: act_ct: fix nf_connlabels leak on two error paths

tcf_ct_fill_params() calls nf_connlabels_get() (setting put_labels) when
TCA_CT_LABELS is present, but two later error sites use a bare return
instead of "goto err", skipping the err: nf_connlabels_put() cleanup.
They also precede the "p->put_labels = put_labels" assignment, so the
tcf_ct_params_free() fallback does not release the count either. Each
failed RTM_NEWACTION on these paths leaks one nf_connlabels reference:
net->ct.labels_used is incremented and never released. The action is
reachable with CAP_NET_ADMIN over the netns, i.e. from an unprivileged
user namespace on default-userns kernels.

Impact: an unprivileged user with CAP_NET_ADMIN over a network namespace
(e.g. via user namespaces) leaks one nf_connlabels reference per failed
RTM_NEWACTION on the two error paths; net->ct.labels_used is never
released.

The err: label is safe to reach from both sites: p->tmpl is still NULL
there (kzalloc'd, not yet assigned) and nf_ct_put(NULL) is a no-op, so
no inline release is needed.

The Linux kernel CVE team has assigned CVE-2026-72430 to this issue.


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

	Issue introduced in 6.7 with commit 70f06c115bcca26ceeebf938e48bc8143668e38b and fixed in 6.12.97 with commit 13b561c893c741635adce3781490a7a1099106c8
	Issue introduced in 6.7 with commit 70f06c115bcca26ceeebf938e48bc8143668e38b and fixed in 6.18.40 with commit 1d51aff78f078af1a80e9496c2f4643f4c0ef0a0
	Issue introduced in 6.7 with commit 70f06c115bcca26ceeebf938e48bc8143668e38b and fixed in 7.1.5 with commit 0c3d8fc87e10e38fe054ece009d6d1f66bef2cd4
	Issue introduced in 6.7 with commit 70f06c115bcca26ceeebf938e48bc8143668e38b and fixed in 7.2-rc1 with commit 16e088016f38cf728a0de709c3335cc5a3850476

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-2026-72430
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/sched/act_ct.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/13b561c893c741635adce3781490a7a1099106c8
	https://git.kernel.org/stable/c/1d51aff78f078af1a80e9496c2f4643f4c0ef0a0
	https://git.kernel.org/stable/c/0c3d8fc87e10e38fe054ece009d6d1f66bef2cd4
	https://git.kernel.org/stable/c/16e088016f38cf728a0de709c3335cc5a3850476