Date:   Wed, 24 Nov 2021 14:15:10 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Jason Gunthorpe <jgg@nvidia.com>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        syzbot+e4df4e1389e28972e955@syzkaller.appspotmail.com,
        Ziyang Xuan <william.xuanziyang@huawei.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH 4.14 181/251] net: vlan: fix a UAF in vlan_dev_real_dev()
Message-ID: <YZ463j6mlk/UUwar@kroah.com>
References: <20211124115710.214900256@linuxfoundation.org>
 <20211124115716.547727004@linuxfoundation.org>
 <20211124125018.GG4670@nvidia.com>
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On Wed, Nov 24, 2021 at 08:50:18AM -0400, Jason Gunthorpe wrote:
> On Wed, Nov 24, 2021 at 12:57:03PM +0100, Greg Kroah-Hartman wrote:
> > From: Ziyang Xuan <william.xuanziyang@huawei.com>
> > 
> > [ 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@syzkaller.appspotmail.com
> > Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
> > Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> > Signed-off-by: David S. Miller <davem@davemloft.net>
> > Signed-off-by: Sasha Levin <sashal@kernel.org>
> > ---
> >  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

It is already in a bunch of branches :(

What is the upstream revert of this commit in Linus's tree?

thanks,

greg k-h