CVE-2024-26923

CVE Details

Release Date:

2024-04-24

Description

In the Linux kernel, the following vulnerability has been resolved:\naf_unix: Fix garbage collector racing against connect()\nGarbage collector does not take into account the risk of embryo getting\nenqueued during the garbage collection. If such embryo has a peer that\ncarries SCM_RIGHTS, two consecutive passes of scan_children() may see a\ndifferent set of children. Leading to an incorrectly elevated inflight\ncount, and then a dangling pointer within the gc_inflight_list.\nsockets are AF_UNIX/SOCK_STREAM\nS is an unconnected socket\nL is a listening in-flight socket bound to addr, not in fdtable\nV's fd will be passed via sendmsg(), gets inflight count bumped\nconnect(S, addr)sendmsg(S, [V]); close(V)__unix_gc()\n----------------------------------------------------\nNS = unix_create1()\nskb1 = sock_wmalloc(NS)\nL = unix_find_other(addr)\nunix_state_lock(L)\nunix_peer(S) = NS\n// V count=1 inflight=0\nNS = unix_peer(S)\nskb2 = sock_alloc()\nskb_queue_tail(NS, skb2[V])\n// V became in-flight\n// V count=2 inflight=1\nclose(V)\n// V count=1 inflight=1\n// GC candidate condition met\nfor u in gc_inflight_list:\nif (total_refs == inflight_refs)\nadd u to gc_candidates\n// gc_candidates={L, V}\nfor u in gc_candidates:\nscan_children(u, dec_inflight)\n// embryo (skb1) was not\n// reachable from L yet, so V's\n// inflight remains unchanged\n__skb_queue_tail(L, skb1)\nunix_state_unlock(L)\nfor u in gc_candidates:\nif (u.inflight)\nscan_children(u, inc_inflight_move_tail)\n// V count=1 inflight=2 (!)\nIf there is a GC-candidate listening socket, lock/unlock its state. This\nmakes GC wait until the end of any ongoing connect() to that socket. After\nflipping the lock, a possibly SCM-laden embryo is already enqueued. And if\nthere is another embryo coming, it can not possibly carry SCM_RIGHTS. At\nthis point, unix_inflight() can not happen because unix_gc_lock is already\ntaken. Inflight graph remains unaffected.

See more information about CVE-2024-26923 from MITRE CVE dictionary and NIST NVD

CVSS Scoring

NOTE: The following CVSS v3.1 metrics and score provided are preliminary and subject to review.

Base Score:	7	CVSS Vector:	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector:	Local network	Attack Complexity:	High
Privileges Required:	Low	User Interaction:	None
Scope:	Unchanged	Confidentiality Impact:	High
Integrity Impact:	High	Availability Impact:	High

Errata information

Platform	Errata	Release Date
Oracle Linux version 8 (kernel)	ELSA-2024-7000	2024-09-24
Oracle Linux version 9 (kernel)	ELSA-2024-8617	2024-10-30