xfrm: always flush state and policy upon NETDEV_UNREGISTER event

MITRE NVD CVE.ORG JSON API Print: PDF PDF

Summary

CVECVE-2026-43167
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-06 12:16:34 UTC
Updated2026-05-06 13:07:51 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: xfrm: always flush state and policy upon NETDEV_UNREGISTER event syzbot is reporting that "struct xfrm_state" refcount is leaking. unregister_netdevice: waiting for netdevsim0 to become free. Usage count = 2 ref_tracker: netdev@ffff888052f24618 has 1/1 users at __netdev_tracker_alloc include/linux/netdevice.h:4400 [inline] netdev_tracker_alloc include/linux/netdevice.h:4412 [inline] xfrm_dev_state_add+0x3a5/0x1080 net/xfrm/xfrm_device.c:316 xfrm_state_construct net/xfrm/xfrm_user.c:986 [inline] xfrm_add_sa+0x34ff/0x5fa0 net/xfrm/xfrm_user.c:1022 xfrm_user_rcv_msg+0x58e/0xc00 net/xfrm/xfrm_user.c:3507 netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2550 xfrm_netlink_rcv+0x71/0x90 net/xfrm/xfrm_user.c:3529 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0xa5d/0xc30 net/socket.c:2592 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2646 __sys_sendmsg+0x16d/0x220 net/socket.c:2678 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f This is because commit d77e38e612a0 ("xfrm: Add an IPsec hardware offloading API") implemented xfrm_dev_unregister() as no-op despite xfrm_dev_state_add() from xfrm_state_construct() acquires a reference to "struct net_device". I guess that that commit expected that NETDEV_DOWN event is fired before NETDEV_UNREGISTER event fires, and also assumed that xfrm_dev_state_add() is called only if (dev->features & NETIF_F_HW_ESP) != 0. Sabrina Dubroca identified steps to reproduce the same symptoms as below. echo 0 > /sys/bus/netdevsim/new_device dev=$(ls -1 /sys/bus/netdevsim/devices/netdevsim0/net/) ip xfrm state add src 192.168.13.1 dst 192.168.13.2 proto esp \ spi 0x1000 mode tunnel aead 'rfc4106(gcm(aes))' $key 128 \ offload crypto dev $dev dir out ethtool -K $dev esp-hw-offload off echo 0 > /sys/bus/netdevsim/del_device Like these steps indicate, the NETIF_F_HW_ESP bit can be cleared after xfrm_dev_state_add() acquired a reference to "struct net_device". Also, xfrm_dev_state_add() does not check for the NETIF_F_HW_ESP bit when acquiring a reference to "struct net_device". Commit 03891f820c21 ("xfrm: handle NETDEV_UNREGISTER for xfrm device") re-introduced the NETDEV_UNREGISTER event to xfrm_dev_event(), but that commit for unknown reason chose to share xfrm_dev_down() between the NETDEV_DOWN event and the NETDEV_UNREGISTER event. I guess that that commit missed the behavior in the previous paragraph. Therefore, we need to re-introduce xfrm_dev_unregister() in order to release the reference to "struct net_device" by unconditionally flushing state and policy.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected d77e38e612a017480157fe6d2c1422f42cb5b7e3 166801e49a5b5fc127b8c9e2f110f303cfddfbc3 git Not specified
CNA Linux Linux affected d77e38e612a017480157fe6d2c1422f42cb5b7e3 a3c8fede034fa27892f87c863cbd5493167d17ed git Not specified
CNA Linux Linux affected d77e38e612a017480157fe6d2c1422f42cb5b7e3 59581778792cbaf8ad788f4a21dc663ce986050e git Not specified
CNA Linux Linux affected d77e38e612a017480157fe6d2c1422f42cb5b7e3 8c75c455ecd3bfd2f36abf66edb7021c4fa19ec4 git Not specified
CNA Linux Linux affected d77e38e612a017480157fe6d2c1422f42cb5b7e3 4efa91a28576054aae0e6dad9cba8fed8293aef8 git Not specified
CNA Linux Linux affected 4.12 Not specified
CNA Linux Linux unaffected 4.12 semver Not specified
CNA Linux Linux unaffected 6.6.128 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.75 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.16 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.6 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/166801e49a5b5fc127b8c9e2f110f303cfddfbc3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4efa91a28576054aae0e6dad9cba8fed8293aef8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8c75c455ecd3bfd2f36abf66edb7021c4fa19ec4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/59581778792cbaf8ad788f4a21dc663ce986050e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a3c8fede034fa27892f87c863cbd5493167d17ed 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
© CVE.report 2026 |

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report