CVE - CVE-2025-21864

CVE-ID
CVE-2025-21864	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
Description
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.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/69cafd9413084cd5012cf5d7c7ec6f3d493726d9 URL:https://git.kernel.org/stable/c/69cafd9413084cd5012cf5d7c7ec6f3d493726d9 MISC:https://git.kernel.org/stable/c/87858bbf21da239ace300d61dd209907995c0491 URL:https://git.kernel.org/stable/c/87858bbf21da239ace300d61dd209907995c0491 MISC:https://git.kernel.org/stable/c/9b6412e6979f6f9e0632075f8f008937b5cd4efd URL:https://git.kernel.org/stable/c/9b6412e6979f6f9e0632075f8f008937b5cd4efd MISC:https://git.kernel.org/stable/c/cd34a07f744451e2ecf9005bb7d24d0b2fb83656 URL:https://git.kernel.org/stable/c/cd34a07f744451e2ecf9005bb7d24d0b2fb83656 MISC:https://git.kernel.org/stable/c/f1d5e6a5e468308af7759cf5276779d3155c5e98 URL:https://git.kernel.org/stable/c/f1d5e6a5e468308af7759cf5276779d3155c5e98
Assigning CNA
kernel.org
Date Record Created
20241229	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20241229)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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