• Ziyang Xuan's avatar
    net: vlan: fix a UAF in vlan_dev_real_dev() · 563bcbae
    Ziyang Xuan authored
    The real_dev of a vlan net_device may be freed after
    unregister_vlan_dev(). Access the real_dev continually by
    vlan_dev_real_dev() will trigger the UAF problem for the
    real_dev like following:
    
    ==================================================================
    BUG: KASAN: use-after-free in vlan_dev_real_dev+0xf9/0x120
    Call Trace:
     kasan_report.cold+0x83/0xdf
     vlan_dev_real_dev+0xf9/0x120
     is_eth_port_of_netdev_filter.part.0+0xb1/0x2c0
     is_eth_port_of_netdev_filter+0x28/0x40
     ib_enum_roce_netdev+0x1a3/0x300
     ib_enum_all_roce_netdevs+0xc7/0x140
     netdevice_event_work_handler+0x9d/0x210
    ...
    
    Freed by task 9288:
     kasan_save_stack+0x1b/0x40
     kasan_set_track+0x1c/0x30
     kasan_set_free_info+0x20/0x30
     __kasan_slab_free+0xfc/0x130
     slab_free_freelist_hook+0xdd/0x240
     kfree+0xe4/0x690
     kvfree+0x42/0x50
     device_release+0x9f/0x240
     kobject_put+0x1c8/0x530
     put_device+0x1b/0x30
     free_netdev+0x370/0x540
     ppp_destroy_interface+0x313/0x3d0
    ...
    
    Move the put_device(real_dev) to vlan_dev_free(). Ensure
    real_dev not be freed before vlan_dev unregistered.
    
    Fixes: 1da177e4 ("Linux-2.6.12-rc2")
    Reported-by: syzbot+e4df4e1389e28972e955@syzkaller.appspotmail.com
    Signed-off-by: default avatarZiyang Xuan <william.xuanziyang@huawei.com>
    Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    563bcbae
vlan.c 17.6 KB