netdev - Re: [PATCH 1/1] net: bridge: fix a bug on using a neighbour cache entry without checking its state

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Date:   Tue, 8 Jan 2019 14:04:04 +0800
From:   kchen <kchen@...ology.com>
To:     David Miller <davem@...emloft.net>
Cc:     nikolay@...ulusnetworks.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, JianJhen Chen <kchen@...ology.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] net: bridge: fix a bug on using a neighbour cache
 entry without checking its state


From: David Miller <davem@...emloft.net>
Date: Mon, 07 Jan 2019 09:10:31 -0800

 > From: David Miller <davem@...emloft.net>
 >
> From: kchen <kchen@...ology.com>
> Date: Sun,  6 Jan 2019 11:28:13 +0800
> 
>> From: JianJhen Chen <kchen@...ology.com>
>>
>> When handling DNAT'ed packets on a bridge device, the neighbour cache entry
>> from lookup was used without checking its state. It means that a cache entry
>> in the NUD_STALE state will be used directly instead of entering the NUD_DELAY
>> state to confirm the reachability of the neighbor.
>>
>> This problem becomes worse after commit 2724680bceee ("neigh: Keep neighbour
>> cache entries if number of them is small enough."), since all neighbour cache
>> entries in the NUD_STALE state will be kept in the neighbour table as long as
>> the number of cache entries does not exceed the value specified in gc_thresh1.
>>
>> This commit validates the state of a neighbour cache entry before using
>> the entry.
>>
>> Signed-off-by: JianJhen Chen <kchen@...ology.com>
>> Reviewed-by: JinLin Chen <jlchen@...ology.com>
> 
> Indeed, this looks correct.
> 
> Applied and queued up for -stable, thanks.
> 

Thank you for the confirmation.