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Amazon Linux 2023: CVE-2024-26923: Medium priority package update for kernel

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Amazon Linux 2023: CVE-2024-26923: Medium priority package update for kernel

Severity
6
CVSS
(AV:L/AC:H/Au:S/C:C/I:C/A:C)
Published
04/24/2024
Created
02/14/2025
Added
02/14/2025
Modified
02/14/2025

Description

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. A flaw was found in the Linux kernel, where the management of inter-process communication uses AF_UNIX sockets. The issue arises from a race condition where a partially initialized socket with specific permissions carrying SCM_RIGHTS is improperly handled during garbage collection. This situation leads to an incorrect count of active sockets, potentially causing resources to remain unaccounted for and never released.

Solution(s)

  • amazon-linux-2023-upgrade-bpftool
  • amazon-linux-2023-upgrade-bpftool-debuginfo
  • amazon-linux-2023-upgrade-kernel
  • amazon-linux-2023-upgrade-kernel-debuginfo
  • amazon-linux-2023-upgrade-kernel-debuginfo-common-aarch64
  • amazon-linux-2023-upgrade-kernel-debuginfo-common-x86-64
  • amazon-linux-2023-upgrade-kernel-devel
  • amazon-linux-2023-upgrade-kernel-headers
  • amazon-linux-2023-upgrade-kernel-libbpf
  • amazon-linux-2023-upgrade-kernel-libbpf-devel
  • amazon-linux-2023-upgrade-kernel-libbpf-static
  • amazon-linux-2023-upgrade-kernel-livepatch-6-1-87-99-174
  • amazon-linux-2023-upgrade-kernel-modules-extra
  • amazon-linux-2023-upgrade-kernel-modules-extra-common
  • amazon-linux-2023-upgrade-kernel-tools
  • amazon-linux-2023-upgrade-kernel-tools-debuginfo
  • amazon-linux-2023-upgrade-kernel-tools-devel
  • amazon-linux-2023-upgrade-perf
  • amazon-linux-2023-upgrade-perf-debuginfo
  • amazon-linux-2023-upgrade-python3-perf
  • amazon-linux-2023-upgrade-python3-perf-debuginfo

References

  • https://attackerkb.com/topics/cve-2024-26923
  • CVE - 2024-26923
  • https://alas.aws.amazon.com/AL2023/ALAS-2024-613.html
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