Wind River Support Network

Description

In 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.

CVEs

• CVE-2026-43167