On Wed, Nov 24, 2021 at 12:57:03PM +0100, Greg Kroah-Hartman wrote:
> From: Ziyang Xuan <william.xuanziyang@xxxxxxxxxx>
>
> [ Upstream commit 563bcbae3ba233c275c244bfce2efe12938f5363 ]
>
> 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: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Reported-by: syzbot+e4df4e1389e28972e955@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Ziyang Xuan <william.xuanziyang@xxxxxxxxxx>
> Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
> net/8021q/vlan.c | 3 ---
> net/8021q/vlan_dev.c | 3 +++
> 2 files changed, 3 insertions(+), 3 deletions(-)
This patch is known to be broken, it should not be backported
Jason
