netdev - Re: [PATCH] tipc: Fix tipc_sk_reinit handling of -EAGAIN

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Message-ID: <20170824131056.GC14926@gondor.apana.org.au>
Date:   Thu, 24 Aug 2017 21:10:56 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Bob Peterson <rpeterso@...hat.com>
Cc:     Phil Sutter <psutter@...hat.com>, davem@...emloft.net,
        netdev@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tipc: Fix tipc_sk_reinit handling of -EAGAIN

On Wed, Aug 23, 2017 at 10:43:02AM -0400, Bob Peterson wrote:
> Hi,
> 
> In 9dbbfb0ab6680c6a85609041011484e6658e7d3c function tipc_sk_reinit
> had additional logic added to loop in the event that function
> rhashtable_walk_next() returned -EAGAIN. No worries.
> 
> However, if rhashtable_walk_start returns -EAGAIN, it does "continue",
> and therefore skips the call to rhashtable_walk_stop(). That has
> the effect of calling rcu_read_lock() without its paired call to
> rcu_read_unlock(). Since rcu_read_lock() may be nested, the problem
> may not be apparent for a while, especially since resize events may
> be rare. But the comments to rhashtable_walk_start() state:
> 
>  * ...Note that we take the RCU lock in all
>  * cases including when we return an error.  So you must always call
>  * rhashtable_walk_stop to clean up.
> 
> This patch replaces the continue with a goto and label to ensure a
> matching call to rhashtable_walk_stop().
> 
> Signed-off-by: Bob Peterson <rpeterso@...hat.com>

Acked-by: Herbert Xu <herbert@...dor.apana.org.au>

Thanks for catching this!
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt