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CVE PROGRAM SOURCE RECORD7.8 High

CVE-2026-64581

xfrm: fix sk_dst_cache double-free in xfrm_user_policy()

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: xfrm: fix sk_dst_cache double-free in xfrm_user_policy() xfrm_user_policy() clears the socket dst cache with __sk_dst_reset(), i.e. the non-atomic __sk_dst_set(sk, NULL): it reads sk_dst_cache with rcu_dereference_protected(), stores NULL and dst_release()s the old dst. That is only safe if no other thread modifies sk_dst_cache concurrently. For a connected UDP socket that does not hold: the transmit fast path (udp_sendmsg -> sk_dst_check -> sk_dst_reset) resets the cache locklessly with an atomic xchg(). A per-socket policy change racing a send can make both sides observe the same old dst and each dst_release() it, dropping the socket's single reference twice and freeing the xfrm_dst bundle while it is still referenced: BUG: KASAN: slab-use-after-free in dst_release Write of size 4 at addr ffff88801897b6c0 by task exploit/155 Call Trace: ... dst_release (... ./include/linux/rcuref.h:109) xfrm_user_policy (./include/net/sock.h:2239 ./include/net/sock.h:2256 net/xfrm/xfrm_state.c:3053) do_ip_setsockopt (net/ipv4/ip_sockglue.c:1347) ip_setsockopt (net/ipv4/ip_sockglue.c:1417) do_sock_setsockopt (net/socket.c:2368) __sys_setsockopt (net/socket.c:2393) __x64_sys_setsockopt (net/socket.c:2396) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) Reachable by an unprivileged user via a user+network namespace. Use the atomic sk_dst_reset() so the cache is cleared and released with a single xchg(): whichever side wins releases the dst once, the other sees NULL and does nothing. Behaviour is otherwise unchanged.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 to < e8686fd8d18b99f3a9038683045b2f2338a7706daffected
  • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 to < a9340ebdc13f8bb5063c0bc0b037ee7e640d4ae9affected
  • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 to < f833821e4b52ab6335d443ede5fb79c38e61d19aaffected
  • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 to < f0ab9a71167bae308e05ab13b65e2007504a603faffected
  • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 to < 8dd8929b71c4f06c614f8f54c2cc070453faae16affected
  • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 to < 0ea8f06454012d9e7f9c6e6253df710949bf6294affected
  • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 to < 96b678d08268b5f5c6fc99d4289d9b7e334fc683affected
  • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 to < c283e9ada7fcb7dd4b10592623086b2e6d2f9925affected
  • 72f157be2f81910ae759bfe2e5c2256fc4625645affected
  • 9e9fe58a92a46c6d154d2901735bf230d91b8507affected
  • adc1ec6cdc20d430aa01b86497220709b9149466affected
  • b54033eb1cfd77aba471269ddd804ed8d3e35deaaffected
  • c9e82cb34c3c2ee895af01bc899c6ed0bc6eb04aaffected
  • 5eef9b51114fcc65651d671add52f267f91b9451affected
  • 3.16.52 to < 3.17affected
  • 4.4.163 to < 4.5affected
  • 3.18.101 to < 3.19affected
  • 4.1.52 to < 4.2affected
  • 4.4.123 to < 4.5affected
  • 4.9.89 to < 4.10affected

Linux Linux

Default version status: affected

  • 4.14affected
  • 0 to < 4.14unaffected
  • 5.10.267 to ≤ 5.10.*unaffected
  • 5.15.218 to ≤ 5.15.*unaffected
  • 6.1.185 to ≤ 6.1.*unaffected
  • 6.6.154 to ≤ 6.6.*unaffected
  • 6.12.106 to ≤ 6.12.*unaffected
  • 6.18.47 to ≤ 6.18.*unaffected
  • 7.1.6 to ≤ 7.1.*unaffected
  • 7.2 to ≤ *unaffected

References