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

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

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.

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Linux kernel 安全漏洞

Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel 6.7版本存在安全漏洞，该漏洞源于net/sched/act_ct的tcf_ct_fill_params函数在两条错误路径上未正确释放nf_connlabels引用，可能导致具有CAP_NET_ADMIN权限的未授权用户通过用户命名空间造成资源泄漏。

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