Alvin Šipraga
authored
If a bridged port is not offloaded to the hardware - either because the underlying driver does not implement the port_bridge_{join,leave} ops, or because the operation failed - then its dp->bridge pointer will be NULL when dsa_port_bridge_leave() is called. Avoid dereferncing NULL. This fixes the following splat when removing a port from a bridge: Unable to handle kernel access to user memory outside uaccess routines at virtual address 0000000000000000 Internal error: Oops: 96000004 [#1] PREEMPT_RT SMP CPU: 3 PID: 1119 Comm: brctl Tainted: G O 5.17.0-rc4-rt4 #1 Call trace: dsa_port_bridge_leave+0x8c/0x1e4 dsa_slave_changeupper+0x40/0x170 dsa_slave_netdevice_event+0x494/0x4d4 notifier_call_chain+0x80/0xe0 raw_notifier_call_chain+0x1c/0x24 call_netdevice_notifiers_info+0x5c/0xac __netdev_upper_dev_unlink+0xa4/0x200 netdev_upper_dev_unlink+0x38/0x60 del_nbp+0x1b0/0x300 br_del_if+0x38/0x114 add_del_if+0x6...