Re: [PATCH net 3/4] bonding: fix xfrm real_dev null pointer dereference

[Hangbin Liu <liuhangbin@gmail.com>]

On Fri, Aug 16, 2024 at 02:48:12PM +0300, Nikolay Aleksandrov wrote:
> We shouldn't set real_dev to NULL because packets can be in transit and
> xfrm might call xdo_dev_offload_ok() in parallel. All callbacks assume
> real_dev is set.
> 
>  Example trace:
>  kernel: BUG: unable to handle page fault for address: 0000000000001030
>  kernel: bond0: (slave eni0np1): making interface the new active one
>  kernel: #PF: supervisor write access in kernel mode
>  kernel: #PF: error_code(0x0002) - not-present page
>  kernel: PGD 0 P4D 0
>  kernel: Oops: 0002 [#1] PREEMPT SMP
>  kernel: CPU: 4 PID: 2237 Comm: ping Not tainted 6.7.7+ #12
>  kernel: Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014
>  kernel: RIP: 0010:nsim_ipsec_offload_ok+0xc/0x20 [netdevsim]
>  kernel: bond0: (slave eni0np1): bond_ipsec_add_sa_all: failed to add SA

I saw the errors are during bond_ipsec_add_sa_all, which also
set ipsec->xs->xso.real_dev = NULL. Should we fix it there?

Thanks
Hangbin
>  kernel: Code: e0 0f 0b 48 83 7f 38 00 74 de 0f 0b 48 8b 47 08 48 8b 37 48 8b 78 40 e9 b2 e5 9a d7 66 90 0f 1f 44 00 00 48 8b 86 80 02 00 00 <83> 80 30 10 00 00 01 b8 01 00 00 00 c3 0f 1f 80 00 00 00 00 0f 1f
>  kernel: bond0: (slave eni0np1): making interface the new active one
>  kernel: RSP: 0018:ffffabde81553b98 EFLAGS: 00010246
>  kernel: bond0: (slave eni0np1): bond_ipsec_add_sa_all: failed to add SA
>  kernel:
>  kernel: RAX: 0000000000000000 RBX: ffff9eb404e74900 RCX: ffff9eb403d97c60
>  kernel: RDX: ffffffffc090de10 RSI: ffff9eb404e74900 RDI: ffff9eb3c5de9e00
>  kernel: RBP: ffff9eb3c0a42000 R08: 0000000000000010 R09: 0000000000000014
>  kernel: R10: 7974203030303030 R11: 3030303030303030 R12: 0000000000000000
>  kernel: R13: ffff9eb3c5de9e00 R14: ffffabde81553cc8 R15: ffff9eb404c53000
>  kernel: FS:  00007f2a77a3ad00(0000) GS:ffff9eb43bd00000(0000) knlGS:0000000000000000
>  kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  kernel: CR2: 0000000000001030 CR3: 00000001122ab000 CR4: 0000000000350ef0
>  kernel: bond0: (slave eni0np1): making interface the new active one
>  kernel: Call Trace:
>  kernel:  <TASK>
>  kernel:  ? __die+0x1f/0x60
>  kernel: bond0: (slave eni0np1): bond_ipsec_add_sa_all: failed to add SA
>  kernel:  ? page_fault_oops+0x142/0x4c0
>  kernel:  ? do_user_addr_fault+0x65/0x670
>  kernel:  ? kvm_read_and_reset_apf_flags+0x3b/0x50
>  kernel: bond0: (slave eni0np1): making interface the new active one
>  kernel:  ? exc_page_fault+0x7b/0x180
>  kernel:  ? asm_exc_page_fault+0x22/0x30
>  kernel:  ? nsim_bpf_uninit+0x50/0x50 [netdevsim]
>  kernel: bond0: (slave eni0np1): bond_ipsec_add_sa_all: failed to add SA
>  kernel:  ? nsim_ipsec_offload_ok+0xc/0x20 [netdevsim]
>  kernel: bond0: (slave eni0np1): making interface the new active one
>  kernel:  bond_ipsec_offload_ok+0x7b/0x90 [bonding]
>  kernel:  xfrm_output+0x61/0x3b0
>  kernel: bond0: (slave eni0np1): bond_ipsec_add_sa_all: failed to add SA
>  kernel:  ip_push_pending_frames+0x56/0x80
> 
> Fixes: 18cb261afd7b ("bonding: support hardware encryption offload to slaves")
> Signed-off-by: Nikolay Aleksandrov <razor@blackwall.org>
> ---
>  drivers/net/bonding/bond_main.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 65ddb71eebcd..f74bacf071fc 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -582,7 +582,6 @@ static void bond_ipsec_del_sa_all(struct bonding *bond)
>  		} else {
>  			slave->dev->xfrmdev_ops->xdo_dev_state_delete(ipsec->xs);
>  		}
> -		ipsec->xs->xso.real_dev = NULL;
>  	}
>  	spin_unlock_bh(&bond->ipsec_lock);
>  	rcu_read_unlock();
> -- 
> 2.44.0
>