CVE ID :CVE-2026-46242<\/p>\n
Published : May 30, 2026, 1:16 p.m. | 1\u00a0hour, 16\u00a0minutes ago<\/p>\n
Description :In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
eventpoll: fix ep_remove struct eventpoll \/ struct file UAF<\/p>\n
ep_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().<\/p>\n
For 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.<\/p>\n
In 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.<\/p>\n
Pin @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.<\/p>\n
If 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.<\/p>\n
A 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.<\/p>\n
Severity: 0.0 | NA<\/p>\n
Visit the link for more details, such as CVSS details, affected products, timeline, and more…\u00a0<\/p>\n","protected":false},"excerpt":{"rendered":"
CVE ID :CVE-2026-46242 Published : May 30, 2026, 1:16 p.m. | 1\u00a0hour, 16\u00a0minutes ago Description :In the Linux kernel, the following vulnerability has been resolved: eventpoll: fix ep_remove struct eventpoll \/ struct file UAF ep_remove() (via ep_remove_file()) cleared file->f_ep under file->f_lock but then kept using @file inside the critical section (is_file_epoll(), hlist_del_rcu() through the head, …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[],"class_list":["post-79053","post","type-post","status-publish","format-standard","hentry","category-vulnerability"],"_links":{"self":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts\/79053","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/comments?post=79053"}],"version-history":[{"count":0,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts\/79053\/revisions"}],"wp:attachment":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/media?parent=79053"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/categories?post=79053"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/tags?post=79053"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}