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Date:   Fri, 6 Dec 2019 14:26:59 +0000
From:   Jon Maloy <jon.maloy@...csson.com>
To:     Taehee Yoo <ap420073@...il.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "ying.xue@...driver.com" <ying.xue@...driver.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH v2 net] tipc: fix ordering of tipc module init and exit
 routine

Acked-by: Jon Maloy <jon.maloy@...csson.com>

> -----Original Message-----
> From: Taehee Yoo <ap420073@...il.com>
> Sent: 6-Dec-19 00:26
> To: davem@...emloft.net; Jon Maloy <jon.maloy@...csson.com>; ying.xue@...driver.com;
> netdev@...r.kernel.org
> Cc: ap420073@...il.com
> Subject: [PATCH v2 net] tipc: fix ordering of tipc module init and exit routine
> 
> In order to set/get/dump, the tipc uses the generic netlink
> infrastructure. So, when tipc module is inserted, init function
> calls genl_register_family().
> After genl_register_family(), set/get/dump commands are immediately
> allowed and these callbacks internally use the net_generic.
> net_generic is allocated by register_pernet_device() but this
> is called after genl_register_family() in the __init function.
> So, these callbacks would use un-initialized net_generic.
> 
> Test commands:
>     #SHELL1
>     while :
>     do
>         modprobe tipc
>         modprobe -rv tipc
>     done
> 
>     #SHELL2
>     while :
>     do
>         tipc link list
>     done
> 
> Splat looks like:
> [   59.616322][ T2788] kasan: CONFIG_KASAN_INLINE enabled
> [   59.617234][ T2788] kasan: GPF could be caused by NULL-ptr deref or user memory access
> [   59.618398][ T2788] general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI
> [   59.619389][ T2788] CPU: 3 PID: 2788 Comm: tipc Not tainted 5.4.0+ #194
> [   59.620231][ T2788] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox
> 12/01/2006
> [   59.621428][ T2788] RIP: 0010:tipc_bcast_get_broadcast_mode+0x131/0x310 [tipc]
> [   59.622379][ T2788] Code: c7 c6 ef 8b 38 c0 65 ff 0d 84 83 c9 3f e8 d7 a5 f2 e3 48 8d bb 38 11 00 00 48
> b8 00 00 00 00
> [   59.622550][ T2780] NET: Registered protocol family 30
> [   59.624627][ T2788] RSP: 0018:ffff88804b09f578 EFLAGS: 00010202
> [   59.624630][ T2788] RAX: dffffc0000000000 RBX: 0000000000000011 RCX: 000000008bc66907
> [   59.624631][ T2788] RDX: 0000000000000229 RSI: 000000004b3cf4cc RDI: 0000000000001149
> [   59.624633][ T2788] RBP: ffff88804b09f588 R08: 0000000000000003 R09: fffffbfff4fb3df1
> [   59.624635][ T2788] R10: fffffbfff50318f8 R11: ffff888066cadc18 R12: ffffffffa6cc2f40
> [   59.624637][ T2788] R13: 1ffff11009613eba R14: ffff8880662e9328 R15: ffff8880662e9328
> [   59.624639][ T2788] FS:  00007f57d8f7b740(0000) GS:ffff88806cc00000(0000)
> knlGS:0000000000000000
> [   59.624645][ T2788] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   59.625875][ T2780] tipc: Started in single node mode
> [   59.626128][ T2788] CR2: 00007f57d887a8c0 CR3: 000000004b140002 CR4: 00000000000606e0
> [   59.633991][ T2788] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [   59.635195][ T2788] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [   59.636478][ T2788] Call Trace:
> [   59.637025][ T2788]  tipc_nl_add_bc_link+0x179/0x1470 [tipc]
> [   59.638219][ T2788]  ? lock_downgrade+0x6e0/0x6e0
> [   59.638923][ T2788]  ? __tipc_nl_add_link+0xf90/0xf90 [tipc]
> [   59.639533][ T2788]  ? tipc_nl_node_dump_link+0x318/0xa50 [tipc]
> [   59.640160][ T2788]  ? mutex_lock_io_nested+0x1380/0x1380
> [   59.640746][ T2788]  tipc_nl_node_dump_link+0x4fd/0xa50 [tipc]
> [   59.641356][ T2788]  ? tipc_nl_node_reset_link_stats+0x340/0x340 [tipc]
> [   59.642088][ T2788]  ? __skb_ext_del+0x270/0x270
> [   59.642594][ T2788]  genl_lock_dumpit+0x85/0xb0
> [   59.643050][ T2788]  netlink_dump+0x49c/0xed0
> [   59.643529][ T2788]  ? __netlink_sendskb+0xc0/0xc0
> [   59.644044][ T2788]  ? __netlink_dump_start+0x190/0x800
> [   59.644617][ T2788]  ? __mutex_unlock_slowpath+0xd0/0x670
> [   59.645177][ T2788]  __netlink_dump_start+0x5a0/0x800
> [   59.645692][ T2788]  genl_rcv_msg+0xa75/0xe90
> [   59.646144][ T2788]  ? __lock_acquire+0xdfe/0x3de0
> [   59.646692][ T2788]  ? genl_family_rcv_msg_attrs_parse+0x320/0x320
> [   59.647340][ T2788]  ? genl_lock_dumpit+0xb0/0xb0
> [   59.647821][ T2788]  ? genl_unlock+0x20/0x20
> [   59.648290][ T2788]  ? genl_parallel_done+0xe0/0xe0
> [   59.648787][ T2788]  ? find_held_lock+0x39/0x1d0
> [   59.649276][ T2788]  ? genl_rcv+0x15/0x40
> [   59.649722][ T2788]  ? lock_contended+0xcd0/0xcd0
> [   59.650296][ T2788]  netlink_rcv_skb+0x121/0x350
> [   59.650828][ T2788]  ? genl_family_rcv_msg_attrs_parse+0x320/0x320
> [   59.651491][ T2788]  ? netlink_ack+0x940/0x940
> [   59.651953][ T2788]  ? lock_acquire+0x164/0x3b0
> [   59.652449][ T2788]  genl_rcv+0x24/0x40
> [   59.652841][ T2788]  netlink_unicast+0x421/0x600
> [ ... ]
> 
> Fixes: 7e4369057806 ("tipc: fix a slab object leak")
> Fixes: a62fbccecd62 ("tipc: make subscriber server support net namespace")
> Signed-off-by: Taehee Yoo <ap420073@...il.com>
> ---
> 
> v1 -> v2 : move tipc_netlink_compat_stop() too
> 
>  net/tipc/core.c | 29 +++++++++++++++--------------
>  1 file changed, 15 insertions(+), 14 deletions(-)
> 
> diff --git a/net/tipc/core.c b/net/tipc/core.c
> index 7532a00ac73d..4f6dc74adf45 100644
> --- a/net/tipc/core.c
> +++ b/net/tipc/core.c
> @@ -148,14 +148,6 @@ static int __init tipc_init(void)
>  	sysctl_tipc_rmem[1] = RCVBUF_DEF;
>  	sysctl_tipc_rmem[2] = RCVBUF_MAX;
> 
> -	err = tipc_netlink_start();
> -	if (err)
> -		goto out_netlink;
> -
> -	err = tipc_netlink_compat_start();
> -	if (err)
> -		goto out_netlink_compat;
> -
>  	err = tipc_register_sysctl();
>  	if (err)
>  		goto out_sysctl;
> @@ -180,8 +172,21 @@ static int __init tipc_init(void)
>  	if (err)
>  		goto out_bearer;
> 
> +	err = tipc_netlink_start();
> +	if (err)
> +		goto out_netlink;
> +
> +	err = tipc_netlink_compat_start();
> +	if (err)
> +		goto out_netlink_compat;
> +
>  	pr_info("Started in single node mode\n");
>  	return 0;
> +
> +out_netlink_compat:
> +	tipc_netlink_stop();
> +out_netlink:
> +	tipc_bearer_cleanup();
>  out_bearer:
>  	unregister_pernet_subsys(&tipc_pernet_pre_exit_ops);
>  out_register_pernet_subsys:
> @@ -193,23 +198,19 @@ static int __init tipc_init(void)
>  out_pernet:
>  	tipc_unregister_sysctl();
>  out_sysctl:
> -	tipc_netlink_compat_stop();
> -out_netlink_compat:
> -	tipc_netlink_stop();
> -out_netlink:
>  	pr_err("Unable to start in single node mode\n");
>  	return err;
>  }
> 
>  static void __exit tipc_exit(void)
>  {
> +	tipc_netlink_compat_stop();
> +	tipc_netlink_stop();
>  	tipc_bearer_cleanup();
>  	unregister_pernet_subsys(&tipc_pernet_pre_exit_ops);
>  	unregister_pernet_device(&tipc_topsrv_net_ops);
>  	tipc_socket_stop();
>  	unregister_pernet_device(&tipc_net_ops);
> -	tipc_netlink_stop();
> -	tipc_netlink_compat_stop();
>  	tipc_unregister_sysctl();
> 
>  	pr_info("Deactivated\n");
> --
> 2.17.1

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