{"id":"CVE-2026-63978","revision":"c0d73ee4086c473795471a4bc8aba0eb","records":[{"revision":"c0d73ee4086c473795471a4bc8aba0eb","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-63978","aliases":[],"title":"net/handshake: Drain pending requests at net namespace exit","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/handshake: Drain pending requests at net namespace exit\n\nThe arguments to list_splice_init() in handshake_net_exit() are\nreversed. The call moves the local empty \"requests\" list onto\nhn->hn_requests, leaving the local list empty, so the subsequent\ndrain loop runs zero iterations. Pending handshake requests that\nhad not yet been accepted are not torn down when the net namespace\nis destroyed; each one keeps a reference on a socket file and on\nthe handshake_req allocation.\n\nPass the source and destination in the documented order\n(list_splice_init(list, head) moves list onto head) so the pending\nlist is transferred to the local scratch list and drained through\nhandshake_complete().\n\nFixing the splice direction exposes a list-corruption race. After\nthe splice each req->hr_list still has non-empty link pointers,\nthreading the stack-local scratch list rather than hn_requests.\nA concurrent handshake_req_cancel() -- for example, from sunrpc's\nTLS timeout on a kernel socket whose netns reference was not\ntaken -- finds the request through the rhashtable, calls\nremove_pending(), and sees !list_empty(&req->hr_list).\n__remove_pending_locked() then list_del_init()s an entry off the\nscratch list while the drain iterates, corrupting it. The same\ncall arriving after the drain loop has run list_del() on an\nentry hits LIST_POISON instead.\n\nHave remove_pending() check HANDSHAKE_F_NET_DRAINING under\nhn_lock and report not-found when drain is in progress. The\ndrain has already taken ownership; handshake_complete()'s existing\ntest_and_set on HANDSHAKE_F_REQ_COMPLETED still arbitrates\nbetween drain and cancel for who calls the consumer's hp_done. Use\nlist_del_init() rather than list_del() in the drain so req->hr_list\ndoes not carry LIST_POISON after drain releases the entry.\n\nThe DRAINING guard in remove_pending() makes cancel return false,\nbut cancel still falls through to test_and_set_bit on\nHANDSHAKE_F_REQ_COMPLETED and drops the request's hr_file reference.\nWithout another pin, if that is the last reference, sk_destruct frees\nthe request while it is still linked on the drain loop's local list.\nPin each request's hr_file under hn_lock before releasing the list,\nand drop that drain pin after the loop finishes with the request.","state":0,"publishedAt":"2026-07-19T14:56:02.484+00:00","modifiedAt":"2026-10-21T12:42:49.209+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/handshake/netlink.c\",\n \"net/handshake/request.c\"\n ],\n \"versions\": [\n {\n \"version\": \"3b3009ea8abb713b022d94fba95ec270cf6e7eae\",\n \"lessThan\": \"ee4b2ba9d30155f9945811cd3c0c1b06d45787a9\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"3b3009ea8abb713b022d94fba95ec270cf6e7eae\",\n \"lessThan\": \"9ec20c9a5a04f2c3f1cf65d21f886d7aaa6189cd\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"3b3009ea8abb713b022d94fba95ec270cf6e7eae\",\n \"lessThan\": \"2bf24a7e190aae0ea47c78099938ae056c622e44\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"3b3009ea8abb713b022d94fba95ec270cf6e7eae\",\n \"lessThan\": \"8c35539db0ab0bfa1ea44efab00b053261a69469\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"3b3009ea8abb713b022d94fba95ec270cf6e7eae\",\n \"lessThan\": \"ea5fe6a73ca57e5150b8a38b341aef2636eb72f0\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/handshake/netlink.c\",\n \"net/handshake/request.c\"\n ],\n \"versions\": [\n {\n \"version\": \"6.4\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"6.4\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.160\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.93\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.44\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.0.12\",\n \"lessThanOrEqual\": \"7.0.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.1\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8,"severity":"CRITICAL"}],"references":["https://git.kernel.org/stable/c/ee4b2ba9d30155f9945811cd3c0c1b06d45787a9","https://git.kernel.org/stable/c/9ec20c9a5a04f2c3f1cf65d21f886d7aaa6189cd","https://git.kernel.org/stable/c/2bf24a7e190aae0ea47c78099938ae056c622e44","https://git.kernel.org/stable/c/8c35539db0ab0bfa1ea44efab00b053261a69469","https://git.kernel.org/stable/c/ea5fe6a73ca57e5150b8a38b341aef2636eb72f0"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-63978","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-63978","identifiers":["CVE-2026-63978"]},"retained":false,"historicalAffected":[]}],"coverage":[]}