mptcp: pm: fix memory leak from alloc-during-teardown race

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Summary

CVECVE-2026-80784
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-04 16:18:04 UTC
Updated2026-09-04 16:18:04 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: mptcp: pm: fix memory leak from alloc-during-teardown race mptcp_pm_destroy() empties msk->pm.anno_list and msk->pm.userspace_pm_local_addr_list under msk->pm.lock during socket teardown, dropping the lock between the two. A concurrent userspace PM genl ANNOUNCE on the same msk holds a sock reference via mptcp_token_get_sock() and, in mptcp_pm_nl_announce_doit(), calls mptcp_userspace_pm_append_new_local_addr() and mptcp_pm_announced_alloc(). Both take msk->pm.lock briefly to add to their respective lists. Because the genl handler holds a sock reference, mptcp_pm_destroy() may run on the same msk via mptcp_disconnect(), which invokes mptcp_destroy_common() without dropping the sock refcount, before the handler completes. If the lock acquisitions interleave such that mptcp_pm_destroy() empties a list first, the later alloc adds its entry to a list head that nothing else iterates for this msk, and the entry leaks. kmemleak reports both mptcp_pm_add_addr objects (from mptcp_pm_announced_alloc()) and mptcp_pm_addr_entry objects (from mptcp_userspace_pm_append_new_local_addr()) under sustained concurrent ANNOUNCE + close load against the userspace PM. Add an MPTCP_PM_DESTROYING bit in msk->pm.status, set by mptcp_pm_destroy() under pm.lock before the lists are emptied and checked under pm.lock by the alloc paths. Either the alloc takes pm.lock first, in which case its entry is on the list when mptcp_pm_destroy() frees it; or mptcp_pm_destroy() takes pm.lock first, in which case the later alloc observes the bit and refuses. Found by an MPTCP protocol-flow harness extending BRF (arXiv:2305.08782).

Risk And Classification

EPSS: 0.001730000 probability, percentile 0.068310000 (date 2026-09-07)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 9ab4807c84a4aacfc9b4f79cc81254035e0ec361 f48341830e4202db3fe884b819b2db6740f0537d git Not specified
CNA Linux Linux affected 9ab4807c84a4aacfc9b4f79cc81254035e0ec361 bb32e9a6a9a9f99eeda16c4efe443400f3e43892 git Not specified
CNA Linux Linux affected 9ab4807c84a4aacfc9b4f79cc81254035e0ec361 b2a0b55bf613bd3e81ed26a847b0f6b8e6b7f804 git Not specified
CNA Linux Linux affected 9ab4807c84a4aacfc9b4f79cc81254035e0ec361 9fe5eebb664ecdba88f3fde18062d94b1d1c465f git Not specified
CNA Linux Linux affected 9ab4807c84a4aacfc9b4f79cc81254035e0ec361 6c290915a03fc8228b473641025cf762b256dbd2 git Not specified
CNA Linux Linux affected 9ab4807c84a4aacfc9b4f79cc81254035e0ec361 efc33b5102ff859bacd390a5f30112d8e0c084c0 git Not specified
CNA Linux Linux affected 5.19 Not specified
CNA Linux Linux unaffected 5.19 semver Not specified
CNA Linux Linux unaffected 6.1.187 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.154 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.106 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.47 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.11 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/6c290915a03fc8228b473641025cf762b256dbd2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/bb32e9a6a9a9f99eeda16c4efe443400f3e43892 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b2a0b55bf613bd3e81ed26a847b0f6b8e6b7f804 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9fe5eebb664ecdba88f3fde18062d94b1d1c465f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f48341830e4202db3fe884b819b2db6740f0537d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/efc33b5102ff859bacd390a5f30112d8e0c084c0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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