CVE-2025-21864
tcp: drop secpath at the same time as we currently drop dst
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tcp: drop secpath at the same time as we currently drop dst
In the Linux kernel, the following vulnerability has been resolved: tcp: drop secpath at the same time as we currently drop dst Xiumei reported hitting the WARN in xfrm6_tunnel_net_exit while running tests that boil down to: - create a pair of netns - run a basic TCP test over ipcomp6 - delete the pair of netns The xfrm_state found on spi_byaddr was not deleted at the time we delete the netns, because we still have a reference on it. This lingering reference comes from a secpath (which holds a ref on the xfrm_state), which is still attached to an skb. This skb is not leaked, it ends up on sk_receive_queue and then gets defer-free'd by skb_attempt_defer_free. The problem happens when we defer freeing an skb (push it on one CPU's defer_list), and don't flush that list before the netns is deleted. In that case, we still have a reference on the xfrm_state that we don't expect at this point. We already drop the skb's dst in the TCP receive path when it's no longer needed, so let's also drop the secpath. At this point, tcp_filter has already called into the LSM hooks that may require the secpath, so it should not be needed anymore. However, in some of those places, the MPTCP extension has just been attached to the skb, so we cannot simply drop all extensions.
Reserved 2024-12-29 | Published 2025-03-12 | Updated 2025-03-12 | Assigner Linuxgit.kernel.org/...c/87858bbf21da239ace300d61dd209907995c0491
git.kernel.org/...c/f1d5e6a5e468308af7759cf5276779d3155c5e98
git.kernel.org/...c/cd34a07f744451e2ecf9005bb7d24d0b2fb83656
git.kernel.org/...c/69cafd9413084cd5012cf5d7c7ec6f3d493726d9
git.kernel.org/...c/9b6412e6979f6f9e0632075f8f008937b5cd4efd
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