netdev - Re: Race over table->data in proc_do_sync

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Message-ID: <20230810022734.47246-1-kuniyu@amazon.com>
Date: Wed, 9 Aug 2023 19:27:34 -0700
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: <sishuai.system@...il.com>
CC: <horms@...ge.net.au>, <ja@....bg>, <lvs-devel@...r.kernel.org>,
	<netdev@...r.kernel.org>, <kuniyu@...zon.com>
Subject: Re: Race over table->data in proc_do_sync_threshold()

From: Sishuai Gong <sishuai.system@...il.com>
Date: Wed, 9 Aug 2023 20:30:37 -0400
> Hi,
> 
> We observed races over (struct ctl_table *) table->data when two threads
> are running proc_do_sync_threshold() in parallel, as shown below:
> 
> Thread-1			Thread-2
> memcpy(val, valp, sizeof(val)); memcpy(valp, val, sizeof(val));
> 
> This race probably would mess up table->data. Is it better to add a lock?

Yes, we should acquire mutex/seqlock etc.