Subject: Re: [PATCH net-next] net: hsr: init prune_proxy_timer sooner

From: Lukasz Majewski <[email-masked]>
Date: Mon, 29 Apr 2024 10:54:14 +0200

Hi Eric,

> We must initialize prune_proxy_timer before we attempt
> a del_timer_sync() on it.
> 
> syzbot reported the following splat:
> 
> INFO: trying to register non-static key.
> The code is fine but needs lockdep annotation, or maybe
> you didn't initialize this object before use?
> turning off the locking correctness validator.
> CPU: 1 PID: 11 Comm: kworker/u8:1 Not tainted
> 6.9.0-rc5-syzkaller-01199-gfc48de77d69d #0 Hardware name: Google
> Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> Workqueue: netns cleanup_net Call Trace:
>  <TASK>
>   __dump_stack lib/dump_stack.c:88 [inline]
>   dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
>   assign_lock_key+0x238/0x270 kernel/locking/lockdep.c:976
>   register_lock_class+0x1cf/0x980 kernel/locking/lockdep.c:1289
>   __lock_acquire+0xda/0x1fd0 kernel/locking/lockdep.c:5014
>   lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
>   __timer_delete_sync+0x148/0x310 kernel/time/timer.c:1648
>   del_timer_sync include/linux/timer.h:185 [inline]
>   hsr_dellink+0x33/0x80 net/hsr/hsr_netlink.c:132
>   default_device_exit_batch+0x956/0xa90 net/core/dev.c:11737
>   ops_exit_list net/core/net_namespace.c:175 [inline]
>   cleanup_net+0x89d/0xcc0 net/core/net_namespace.c:637
>   process_one_work kernel/workqueue.c:3254 [inline]
>   process_scheduled_works+0xa10/0x17c0 kernel/workqueue.c:3335
>   worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
>   kthread+0x2f0/0x390 kernel/kthread.c:388
>   ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
>   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
>  </TASK>
> ODEBUG: assert_init not available (active state 0) object:
> ffff88806d3fcd88 object type: timer_list hint: 0x0 WARNING: CPU: 1
> PID: 11 at lib/debugobjects.c:517 debug_print_object+0x17a/0x1f0
> lib/debugobjects.c:514
> 
> Fixes: 5055cccfc2d1 ("net: hsr: Provide RedBox support (HSR-SAN)")

Thanks for spotting it.

> Reported-by: syzbot <[email-masked]>
> Signed-off-by: Eric Dumazet <[email-masked]>
> Cc: Lukasz Majewski <[email-masked]>
> ---
>  net/hsr/hsr_device.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/hsr/hsr_device.c b/net/hsr/hsr_device.c
> index
> cd1e7c6d2fc03af0498dc2ce302069699a75cca7..86127300b102fe06eaced32a979e1c8da99339a7
> 100644 --- a/net/hsr/hsr_device.c +++ b/net/hsr/hsr_device.c
> @@ -592,6 +592,7 @@ int hsr_dev_finalize(struct net_device *hsr_dev,
> struct net_device *slave[2], 
>  	timer_setup(&hsr->announce_timer, hsr_announce, 0);
>  	timer_setup(&hsr->prune_timer, hsr_prune_nodes, 0);
> +	timer_setup(&hsr->prune_proxy_timer, hsr_prune_proxy_nodes,
> 0); 
>  	ether_addr_copy(hsr->sup_multicast_addr, def_multicast_addr);
>  	hsr->sup_multicast_addr[ETH_ALEN - 1] = multicast_spec;
> @@ -631,7 +632,6 @@ int hsr_dev_finalize(struct net_device *hsr_dev,
> struct net_device *slave[2], 
>  		hsr->redbox = true;
>  		ether_addr_copy(hsr->macaddress_redbox,
> interlink->dev_addr);
> -		timer_setup(&hsr->prune_proxy_timer,
> hsr_prune_proxy_nodes, 0); mod_timer(&hsr->prune_proxy_timer,
>  			  jiffies +
> msecs_to_jiffies(PRUNE_PROXY_PERIOD)); }

Best regards,

Lukasz Majewski

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