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CVE-2024-26923 Affecting kernel-devel-matched package, versions <0:5.14.0-427.42.1.el9_4

Severity

 Recommended
medium

Based on AlmaLinux security rating

    Threat Intelligence

    EPSS
    0.04% (15th percentile)

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  • Snyk ID SNYK-ALMALINUX9-KERNELDEVELMATCHED-8334916
  • published 4 Nov 2024
  • disclosed 30 Oct 2024
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Introduced: 30 Oct 2024

New CVE-2024-26923 Open this link in a new tab

How to fix?

Upgrade AlmaLinux:9 kernel-devel-matched to version 0:5.14.0-427.42.1.el9_4 or higher.
This issue was patched in ALSA-2024:8617.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-devel-matched package and not the kernel-devel-matched package as distributed by AlmaLinux. See How to fix? for AlmaLinux:9 relevant fixed versions and status.

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&amp;#39;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.

References

CVSS Scores

version 3.1
Expand this section

Red Hat

7 high
  • Attack Vector (AV)
    Local
  • Attack Complexity (AC)
    High
  • Privileges Required (PR)
    Low
  • User Interaction (UI)
    None
  • Scope (S)
    Unchanged
  • Confidentiality (C)
    High
  • Integrity (I)
    High
  • Availability (A)
    High
Expand this section

SUSE

7 high