Deadlock The advisory has been revoked - it doesn't affect any version of package kernel  (opens in a new tab)

The Centos security team deemed this advisory irrelevant for Centos:6.

Note: Versions mentioned in the description apply only to the upstream kernel package and not the kernel package as distributed by Centos.

In the Linux kernel, the following vulnerability has been resolved:

net: Remove RTNL dance for SIOCBRADDIF and SIOCBRDELIF.

SIOCBRDELIF is passed to dev_ioctl() first and later forwarded to br_ioctl_call(), which causes unnecessary RTNL dance and the splat below [0] under RTNL pressure.

Let's say Thread A is trying to detach a device from a bridge and Thread B is trying to remove the bridge.

In dev_ioctl(), Thread A bumps the bridge device's refcnt by netdev_hold() and releases RTNL because the following br_ioctl_call() also re-acquires RTNL.

In the race window, Thread B could acquire RTNL and try to remove the bridge device. Then, rtnl_unlock() by Thread B will release RTNL and wait for netdev_put() by Thread A.

Thread A, however, must hold RTNL after the unlock in dev_ifsioc(), which may take long under RTNL pressure, resulting in the splat by Thread B.

Thread A (SIOCBRDELIF) Thread B (SIOCBRDELBR)

sock_ioctl sock_ioctl - sock_do_ioctl - br_ioctl_call - dev_ioctl - br_ioctl_stub |- rtnl_lock | |- dev_ifsioc ' ' |- dev = __dev_get_by_name(...) |- netdev_hold(dev, ...) . / |- rtnl_unlock ------. | | |- br_ioctl_call ---> |- rtnl_lock Race | | - br_ioctl_stub |- br_del_bridge Window | | | |- dev = __dev_get_by_name(...) | | | May take long | - br_dev_delete(dev, ...) | | | under RTNL pressure | - unregister_netdevice_queue(dev, ...) | | | | - rtnl_unlock \ | |- rtnl_lock <-' - netdev_run_todo | |- ... - netdev_run_todo | - rtnl_unlock |- __rtnl_unlock | |- netdev_wait_allrefs_any |- netdev_put(dev, ...) <----------------' Wait refcnt decrement and log splat below

To avoid blocking SIOCBRDELBR unnecessarily, let's not call dev_ioctl() for SIOCBRADDIF and SIOCBRDELIF.

In the dev_ioctl() path, we do the following:

1. Copy struct ifreq by get_user_ifreq in sock_do_ioctl()

2. Check CAP_NET_ADMIN in dev_ioctl()

3. Call dev_load() in dev_ioctl()

4. Fetch the master dev from ifr.ifr_name in dev_ifsioc()

5. can be done by request_module() in br_ioctl_call(), so we move 1., 2., and 4. to br_ioctl_stub().

Note that 2. is also checked later in add_del_if(), but it's better performed before RTNL.

SIOCBRADDIF and SIOCBRDELIF have been processed in dev_ioctl() since the pre-git era, and there seems to be no specific reason to process them there.

[0]: unregister_netdevice: waiting for wpan3 to become free. Usage count = 2 ref_tracker: wpan3@ffff8880662d8608 has 1/1 users at __netdev_tracker_alloc include/linux/netdevice.h:4282 [inline] netdev_hold include/linux/netdevice.h:4311 [inline] dev_ifsioc+0xc6a/0x1160 net/core/dev_ioctl.c:624 dev_ioctl+0x255/0x10c0 net/core/dev_ioctl.c:826 sock_do_ioctl+0x1ca/0x260 net/socket.c:1213 sock_ioctl+0x23a/0x6c0 net/socket.c:1318 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __x64_sys_ioctl+0x1a4/0x210 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f

• https://access.redhat.com/security/cve/CVE-2025-22111
• https://git.kernel.org/stable/c/00fe0ac64efd1f5373b3dd9f1f84b19235371e39
• https://git.kernel.org/stable/c/ed3ba9b6e280e14cc3148c1b226ba453f02fa76c