{"id":"CVE-2026-46242","revision":"0981b51490164ec883cd9b5cd8a3222e","records":[{"revision":"0981b51490164ec883cd9b5cd8a3222e","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-46242","aliases":[],"title":"eventpoll: fix ep_remove struct eventpoll / struct file UAF","description":"In the Linux kernel, the following vulnerability has been resolved:\n\neventpoll: fix ep_remove struct eventpoll / struct file UAF\n\nep_remove() (via ep_remove_file()) cleared file->f_ep under\nfile->f_lock but then kept using @file inside the critical section\n(is_file_epoll(), hlist_del_rcu() through the head, spin_unlock).\nA concurrent __fput() taking the eventpoll_release() fastpath in\nthat window observed the transient NULL, skipped\neventpoll_release_file() and ran to f_op->release / file_free().\n\nFor the epoll-watches-epoll case, f_op->release is\nep_eventpoll_release() -> ep_clear_and_put() -> ep_free(), which\nkfree()s the watched struct eventpoll. Its embedded ->refs\nhlist_head is exactly where epi->fllink.pprev points, so the\nsubsequent hlist_del_rcu()'s \"*pprev = next\" scribbles into freed\nkmalloc-192 memory.\n\nIn addition, struct file is SLAB_TYPESAFE_BY_RCU, so the slot\nbacking @file could be recycled by alloc_empty_file() --\nreinitializing f_lock and f_ep -- while ep_remove() is still\nnominally inside that lock. The upshot is an attacker-controllable\nkmem_cache_free() against the wrong slab cache.\n\nPin @file via epi_fget() at the top of ep_remove() and gate the\ncritical section on the pin succeeding. With the pin held @file\ncannot reach refcount zero, which holds __fput() off and\ntransitively keeps the watched struct eventpoll alive across the\nhlist_del_rcu() and the f_lock use, closing both UAFs.\n\nIf the pin fails @file has already reached refcount zero and its\n__fput() is in flight. Because we bailed before clearing f_ep,\nthat path takes the eventpoll_release() slow path into\neventpoll_release_file() and blocks on ep->mtx until the waiter\nside's ep_clear_and_put() drops it. The bailed epi's share of\nep->refcount stays intact, so the trailing ep_refcount_dec_and_test()\nin ep_clear_and_put() cannot free the eventpoll out from under\neventpoll_release_file(); the orphaned epi is then cleaned up\nthere.\n\nA successful pin also proves we are not racing\neventpoll_release_file() on this epi, so drop the now-redundant\nre-check of epi->dying under f_lock. The cheap lockless\nREAD_ONCE(epi->dying) fast-path bailout stays.","state":0,"publishedAt":"2026-05-30T12:13:45.594+00:00","modifiedAt":"2026-10-19T19:36:55.705+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                        \"fs/eventpoll.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"f2451def095c1743adcfcb0cb5dadc86034e162a\",\n                            \"lessThan\": \"a10fbbe74e1c743beb1bb312109366667461df8a\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"a1f93804449d13f97dabd4b996817de4bf1ed67a\",\n                            \"lessThan\": \"3e1144d2515d28e4312e663ea05eac203101491d\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"58c9b016e12855286370dfb704c08498edbc857a\",\n                            \"lessThan\": \"2de4db145b2992da496fea6c51f9839be678ae24\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"58c9b016e12855286370dfb704c08498edbc857a\",\n                            \"lessThan\": \"9324de74a3a59b9fde9b62ee45ebaa71458ba2e5\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"58c9b016e12855286370dfb704c08498edbc857a\",\n                            \"lessThan\": \"ef4ca02e95363e78977ca04340d44fe3b4b2b81f\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"58c9b016e12855286370dfb704c08498edbc857a\",\n                            \"lessThan\": \"ced39b6a8062bac5c18a1c3df85634107eb8664a\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"58c9b016e12855286370dfb704c08498edbc857a\",\n                            \"lessThan\": \"a6dc643c69311677c574a0f17a3f4d66a5f3744b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"5.15.209\",\n                            \"lessThan\": \"5.15.222\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.175\",\n                            \"lessThan\": \"6.1.178\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\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                        \"fs/eventpoll.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\": \"5.15.222\",\n                            \"lessThanOrEqual\": \"5.15.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.178\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.144\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.95\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.33\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.0.10\",\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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/a10fbbe74e1c743beb1bb312109366667461df8a","https://git.kernel.org/stable/c/3e1144d2515d28e4312e663ea05eac203101491d","https://git.kernel.org/stable/c/2de4db145b2992da496fea6c51f9839be678ae24","https://git.kernel.org/stable/c/9324de74a3a59b9fde9b62ee45ebaa71458ba2e5","https://git.kernel.org/stable/c/ef4ca02e95363e78977ca04340d44fe3b4b2b81f","https://git.kernel.org/stable/c/ced39b6a8062bac5c18a1c3df85634107eb8664a","https://git.kernel.org/stable/c/a6dc643c69311677c574a0f17a3f4d66a5f3744b"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-46242","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-46242","identifiers":["CVE-2026-46242"]},"retained":false,"historicalAffected":[]}],"coverage":[]}