In the Linux kernel, the following vulnerability has been resolved:

af_unix: Fix garbage collector racing against connect()

Garbage collector does not take into account the risk of embryo getting
enqueued during the garbage collection. If such embryo has a peer that
carries SCM_RIGHTS, two consecutive passes of scan_children() may see a
different set of children. Leading to an incorrectly elevated inflight
count, and then a dangling pointer within the gc_inflight_list.

sockets are AF_UNIX/SOCK_STREAM
S is an unconnected socket
L is a listening in-flight socket bound to addr, not in fdtable
V's fd will be passed via sendmsg(), gets inflight count bumped

connect(S, addr) sendmsg(S, [V]); close(V) __unix_gc()
---------------- ------------------------- -----------

NS = unix_create1()
skb1 = sock_wmalloc(NS)
L = unix_find_other(addr)
unix_state_lock(L)
unix_peer(S) = NS
// V count=1 inflight=0

NS = unix_peer(S)
skb2 = sock_alloc()
skb_queue_tail(NS, skb2[V])

// V became in-flight
// V count=2 inflight=1

close(V)

// V count=1 inflight=1
// GC candidate condition met

for u in gc_inflight_list:
if (total_refs == inflight_refs)
add u to gc_candidates

// gc_candidates={L, V}

for u in gc_candidates:
scan_children(u, dec_inflight)

// embryo (skb1) was not
// reachable from L yet, so V's
// inflight remains unchanged
__skb_queue_tail(L, skb1)
unix_state_unlock(L)
for u in gc_candidates:
if (u.inflight)
scan_children(u, inc_inflight_move_tail)

// V count=1 inflight=2 (!)

If there is a GC-candidate listening socket, lock/unlock its state. This
makes GC wait until the end of any ongoing connect() to that socket. After
flipping the lock, a possibly SCM-laden embryo is already enqueued. And if
there is another embryo coming, it can not possibly carry SCM_RIGHTS. At
this point, unix_inflight() can not happen because unix_gc_lock is already
taken. Inflight graph remains unaffected.
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Fri, 11 Jul 2025 13:45:00 +0000

Type Values Removed Values Added
Metrics epss

{'score': 0.00076}

epss

{'score': 0.00078}


Fri, 22 Nov 2024 12:00:00 +0000


Tue, 05 Nov 2024 10:45:00 +0000


Wed, 30 Oct 2024 15:30:00 +0000

Type Values Removed Values Added
CPEs cpe:/a:redhat:enterprise_linux:9
cpe:/o:redhat:enterprise_linux:9

Wed, 02 Oct 2024 15:00:00 +0000

Type Values Removed Values Added
First Time appeared Redhat rhel Aus
Redhat rhel E4s
Redhat rhel Tus
CPEs cpe:/o:redhat:rhel_aus:8.6
cpe:/o:redhat:rhel_e4s:8.6
cpe:/o:redhat:rhel_tus:8.6
Vendors & Products Redhat rhel Aus
Redhat rhel E4s
Redhat rhel Tus

Tue, 24 Sep 2024 11:15:00 +0000

Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:rhel_eus:8.8

Tue, 24 Sep 2024 06:30:00 +0000

Type Values Removed Values Added
First Time appeared Redhat enterprise Linux
CPEs cpe:/a:redhat:enterprise_linux:8::nfv
Vendors & Products Redhat enterprise Linux

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-05-04T08:59:47.874Z

Reserved: 2024-02-19T14:20:24.194Z

Link: CVE-2024-26923

cve-icon Vulnrichment

Updated: 2024-08-02T00:21:05.612Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2024-04-25T06:15:57.160

Modified: 2024-11-21T09:03:23.543

Link: CVE-2024-26923

cve-icon Redhat

Severity : Moderate

Publid Date: 2024-04-24T00:00:00Z

Links: CVE-2024-26923 - Bugzilla

cve-icon OpenCVE Enrichment

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