CVE-2026-52925

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> vrf: Fix a potential NPD when removing a port from a VRF<br /> <br /> RCU readers that identified a net device as a VRF port using<br /> netif_is_l3_slave() assume that a subsequent call to<br /> netdev_master_upper_dev_get_rcu() will return a VRF device. They then<br /> continue to dereference its l3mdev operations.<br /> <br /> This assumption is not always correct and can result in a NPD [1]. There<br /> is no RCU synchronization when removing a port from a VRF, so it is<br /> possible for an RCU reader to see a new master device (e.g., a bridge)<br /> that does not have l3mdev operations.<br /> <br /> Fix by adding RCU synchronization after clearing the IFF_L3MDEV_SLAVE<br /> flag. Skip this synchronization when a net device is removed from a VRF<br /> as part of its deletion and when the VRF device itself is deleted. In<br /> the latter case an RCU grace period will pass by the time RTNL is<br /> released.<br /> <br /> [1]<br /> BUG: kernel NULL pointer dereference, address: 0000000000000000<br /> [...]<br /> RIP: 0010:l3mdev_fib_table_rcu (net/l3mdev/l3mdev.c:181)<br /> [...]<br /> Call Trace:<br /> <br /> l3mdev_fib_table_by_index (net/l3mdev/l3mdev.c:201 net/l3mdev/l3mdev.c:189)<br /> __inet_bind (net/ipv4/af_inet.c:499 (discriminator 3))<br /> inet_bind_sk (net/ipv4/af_inet.c:469)<br /> __sys_bind (./include/linux/file.h:62 (discriminator 1) ./include/linux/file.h:83 (discriminator 1) net/socket.c:1951 (discriminator 1))<br /> __x64_sys_bind (net/socket.c:1969 (discriminator 1) net/socket.c:1967 (discriminator 1) net/socket.c:1967 (discriminator 1))<br /> do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1))<br /> entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)