{"id":"CVE-2026-80784","summary":"mptcp: pm: fix memory leak from alloc-during-teardown race","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: pm: fix memory leak from alloc-during-teardown race\n\nmptcp_pm_destroy() empties msk-\u003epm.anno_list and\nmsk-\u003epm.userspace_pm_local_addr_list under msk-\u003epm.lock during socket\nteardown, dropping the lock between the two.\n\nA concurrent userspace PM genl ANNOUNCE on the same msk holds a sock\nreference via mptcp_token_get_sock() and, in\nmptcp_pm_nl_announce_doit(), calls\nmptcp_userspace_pm_append_new_local_addr() and\nmptcp_pm_announced_alloc(). Both take msk-\u003epm.lock briefly to add to\ntheir respective lists. Because the genl handler holds a sock reference,\nmptcp_pm_destroy() may run on the same msk via mptcp_disconnect(), which\ninvokes mptcp_destroy_common() without dropping the sock refcount,\nbefore the handler completes.\n\nIf the lock acquisitions interleave such that mptcp_pm_destroy() empties\na list first, the later alloc adds its entry to a list head that nothing\nelse iterates for this msk, and the entry leaks. kmemleak reports both\nmptcp_pm_add_addr objects (from mptcp_pm_announced_alloc()) and\nmptcp_pm_addr_entry objects (from\nmptcp_userspace_pm_append_new_local_addr()) under sustained concurrent\nANNOUNCE + close load against the userspace PM.\n\nAdd an MPTCP_PM_DESTROYING bit in msk-\u003epm.status, set by\nmptcp_pm_destroy() under pm.lock before the lists are emptied and\nchecked under pm.lock by the alloc paths. Either the alloc takes pm.lock\nfirst, in which case its entry is on the list when mptcp_pm_destroy()\nfrees it; or mptcp_pm_destroy() takes pm.lock first, in which case the\nlater alloc observes the bit and refuses.\n\nFound by an MPTCP protocol-flow harness extending BRF (arXiv:2305.08782).","modified":"2026-09-06T03:46:45.645446103Z","published":"2026-09-04T15:12:56.125Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80784.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/6c290915a03fc8228b473641025cf762b256dbd2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9fe5eebb664ecdba88f3fde18062d94b1d1c465f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b2a0b55bf613bd3e81ed26a847b0f6b8e6b7f804"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bb32e9a6a9a9f99eeda16c4efe443400f3e43892"},{"type":"WEB","url":"https://git.kernel.org/stable/c/efc33b5102ff859bacd390a5f30112d8e0c084c0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f48341830e4202db3fe884b819b2db6740f0537d"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80784.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80784"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"9ab4807c84a4aacfc9b4f79cc81254035e0ec361"},{"fixed":"f48341830e4202db3fe884b819b2db6740f0537d"},{"fixed":"bb32e9a6a9a9f99eeda16c4efe443400f3e43892"},{"fixed":"b2a0b55bf613bd3e81ed26a847b0f6b8e6b7f804"},{"fixed":"9fe5eebb664ecdba88f3fde18062d94b1d1c465f"},{"fixed":"6c290915a03fc8228b473641025cf762b256dbd2"},{"fixed":"efc33b5102ff859bacd390a5f30112d8e0c084c0"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80784.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.19.0"},{"fixed":"6.1.187"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.154"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.106"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.47"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.11"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80784.json"}}],"schema_version":"1.9.0"}