af_unix: Fix garbage collector racing against connect()

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Summary

CVECVE-2024-26923
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2024-04-25 06:15:57 UTC
Updated2026-05-12 12:16:26 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 4.7 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-362

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 1fd05ba5a2f2aa8e7b9b52ef55df850e2e7d54c9 a36ae0ec2353015f0f6762e59f4c2dbc0c906423 git Not specified
CNA Linux Linux affected 1fd05ba5a2f2aa8e7b9b52ef55df850e2e7d54c9 343c5372d5e17b306db5f8f3c895539b06e3177f git Not specified
CNA Linux Linux affected 1fd05ba5a2f2aa8e7b9b52ef55df850e2e7d54c9 2e2a03787f4f0abc0072350654ab0ef3324d9db3 git Not specified
CNA Linux Linux affected 1fd05ba5a2f2aa8e7b9b52ef55df850e2e7d54c9 e76c2678228f6aec74b305ae30c9374cc2f28a51 git Not specified
CNA Linux Linux affected 1fd05ba5a2f2aa8e7b9b52ef55df850e2e7d54c9 b75722be422c276b699200de90527d01c602ea7c git Not specified
CNA Linux Linux affected 1fd05ba5a2f2aa8e7b9b52ef55df850e2e7d54c9 507cc232ffe53a352847893f8177d276c3b532a9 git Not specified
CNA Linux Linux affected 1fd05ba5a2f2aa8e7b9b52ef55df850e2e7d54c9 dbdf7bec5c920200077d693193f989cb1513f009 git Not specified
CNA Linux Linux affected 1fd05ba5a2f2aa8e7b9b52ef55df850e2e7d54c9 47d8ac011fe1c9251070e1bd64cb10b48193ec51 git Not specified
CNA Linux Linux affected 2.6.23 Not specified
CNA Linux Linux unaffected 2.6.23 semver Not specified
CNA Linux Linux unaffected 4.19.314 4.19.* semver Not specified
CNA Linux Linux unaffected 5.4.275 5.4.* semver Not specified
CNA Linux Linux unaffected 5.10.216 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.156 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.87 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.28 6.6.* semver Not specified
CNA Linux Linux unaffected 6.8.7 6.8.* semver Not specified
CNA Linux Linux unaffected 6.9 * original_commit_for_fix Not specified
ADP Siemens RUGGEDCOM RST2428P affected V3.1 custom Not specified
ADP Siemens SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 Family unaffected * custom Not specified
ADP Siemens SCALANCE XCM-/XRM-/XCH-/XRH-300 Family affected V3.1 custom Not specified
ADP Siemens SIMATIC S7-1500 TM MFP - GNU/Linux Subsystem affected * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.0 V3.1.5 custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.0 V3.1.5 custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.0 V3.1.5 custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.0 V3.1.5 custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.0 V3.1.5 custom Not specified

References

ReferenceSourceLinkTags
cert-portal.siemens.com/productcert/html/ssa-398330.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
lists.debian.org/debian-lts-announce/2024/06/msg00017.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org Third Party Advisory
git.kernel.org/stable/c/47d8ac011fe1c9251070e1bd64cb10b48193ec51 af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-265688.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/2e2a03787f4f0abc0072350654ab0ef3324d9db3 af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/e76c2678228f6aec74b305ae30c9374cc2f28a51 af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/b75722be422c276b699200de90527d01c602ea7c af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-613116.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/507cc232ffe53a352847893f8177d276c3b532a9 af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
lists.debian.org/debian-lts-announce/2024/06/msg00020.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org Third Party Advisory
git.kernel.org/stable/c/dbdf7bec5c920200077d693193f989cb1513f009 af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/a36ae0ec2353015f0f6762e59f4c2dbc0c906423 af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/343c5372d5e17b306db5f8f3c895539b06e3177f af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
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