netdev - Re: [PATCH net] driver/net: Fix possible memleaks when fail to register

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Message-ID: <20170427081559.GA1058@gondor.apana.org.au>
Date:   Thu, 27 Apr 2017 16:15:59 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     gfree.wind@...mail.com
Cc:     jiri@...nulli.us, davem@...emloft.net, kuznet@....inr.ac.ru,
        jmorris@...ei.org, yoshfuji@...ux-ipv6.org, kaber@...sh.net,
        steffen.klassert@...unet.com, netdev@...r.kernel.org,
        Gao Feng <fgao@...ai8.com>
Subject: Re: [PATCH net] driver/net: Fix possible memleaks when fail to
 register_netdevice

On Tue, Apr 25, 2017 at 08:01:50PM +0800, gfree.wind@...mail.com wrote:
> From: Gao Feng <fgao@...ai8.com>
> 
> These drivers allocate kinds of resources in init routine, and free
> some resources in the destructor of net_device. It may cause memleak
> when some errors happen after register_netdevice invokes the init
> callback. Because only the uninit callback is invoked in the error
> handler of register_netdevice, but the destructor not. As a result,
> some resources are lost forever.
> 
> Now invokes the destructor instead of free_netdev somewhere, and free
> the left resources in the newlink func when fail to register_netdevice.
> 
> Signed-off-by: Gao Feng <fgao@...ai8.com>

This has the potential of creating future bugs, because there
is no guarantee that the ndo_init function has been invoked at
all.

Wouldn't it be safer to move the freeing from the destructors
into their ndo_uninit functions instead?

Thanks,
-- 
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