Subject: Re: [PATCH xfrm 1/2] xfrm: release all offloaded policy memory

From: Leon Romanovsky <[email-masked]>
Date: Thu, 20 Apr 2023 20:04:47 +0300

On Thu, Apr 20, 2023 at 06:51:52PM +0200, Eric Dumazet wrote:
> On Wed, Apr 19, 2023 at 2:19 PM Leon Romanovsky <[email-masked]> wrote:
> >
> > From: Leon Romanovsky <[email-masked]>
> >
> > Failure to add offloaded policy will cause to the following
> > error once user will try to reload driver.
> >
> > Unregister_netdevice: waiting for eth3 to become free. Usage count = 2
> >
> > This was caused by xfrm_dev_policy_add() which increments reference
> > to net_device. That reference was supposed to be decremented
> > in xfrm_dev_policy_free(). However the latter wasn't called.
> >
> >  unregister_netdevice: waiting for eth3 to become free. Usage count = 2
> >  leaked reference.
> >   xfrm_dev_policy_add+0xff/0x3d0
> >   xfrm_policy_construct+0x352/0x420
> >   xfrm_add_policy+0x179/0x320
> >   xfrm_user_rcv_msg+0x1d2/0x3d0
> >   netlink_rcv_skb+0xe0/0x210
> >   xfrm_netlink_rcv+0x45/0x50
> >   netlink_unicast+0x346/0x490
> >   netlink_sendmsg+0x3b0/0x6c0
> >   sock_sendmsg+0x73/0xc0
> >   sock_write_iter+0x13b/0x1f0
> >   vfs_write+0x528/0x5d0
> >   ksys_write+0x120/0x150
> >   do_syscall_64+0x3d/0x90
> >   entry_SYSCALL_64_after_hwframe+0x46/0xb0
> >
> > Fixes: 919e43fad516 ("xfrm: add an interface to offload policy")
> > Signed-off-by: Leon Romanovsky <[email-masked]>
> > ---
> 
> Reviewed-by: Eric Dumazet <[email-masked]>
> 
> While reviewing this patch, I also saw xfrm_dev_policy_add() could use
> GFP_KERNEL ?

netdev_tracker_alloc(...) line was copied from commit e1b539bd73a7
("xfrm: add net device refcount tracker to struct xfrm_state_offload")

Thanks

> 
> diff --git a/net/xfrm/xfrm_device.c b/net/xfrm/xfrm_device.c
> index bef28c6187ebdd0cfc34c8594aab96ac0b13dd24..508c96c90b3911eb88063ad680c77af2b317c95f
> 100644
> --- a/net/xfrm/xfrm_device.c
> +++ b/net/xfrm/xfrm_device.c
> @@ -363,7 +363,7 @@ int xfrm_dev_policy_add(struct net *net, struct
> xfrm_policy *xp,
>         }
> 
>         xdo->dev = dev;
> -       netdev_tracker_alloc(dev, &xdo->dev_tracker, GFP_ATOMIC);
> +       netdev_tracker_alloc(dev, &xdo->dev_tracker, GFP_KERNEL);
>         xdo->real_dev = dev;
>         xdo->type = XFRM_DEV_OFFLOAD_PACKET;
>         switch (dir) {