linux-kernel - Re: [PATCH] can: vxcan: Fix memleak in vxcan

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Message-ID: <20201022091435.2449cf41@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net>
Date:   Thu, 22 Oct 2020 09:14:35 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Oliver Hartkopp <socketcan@...tkopp.net>
Cc:     Dinghao Liu <dinghao.liu@....edu.cn>, kjlu@....edu,
        Wolfgang Grandegger <wg@...ndegger.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        "David S. Miller" <davem@...emloft.net>, linux-can@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] can: vxcan: Fix memleak in vxcan_newlink

On Wed, 21 Oct 2020 13:20:16 +0200 Oliver Hartkopp wrote:
> On 21.10.20 07:21, Dinghao Liu wrote:
> > When rtnl_configure_link() fails, peer needs to be
> > freed just like when register_netdevice() fails.
> > 
> > Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>  
> 
> Acked-by: Oliver Hartkopp <socketcan@...tkopp.net>
> 
> Btw. as the vxcan.c driver bases on veth.c the same issue can be found 
> there!
> 
> At this point:
> https://elixir.bootlin.com/linux/latest/source/drivers/net/veth.c#L1398
> 
> err_register_dev:
>          /* nothing to do */
> err_configure_peer:
>          unregister_netdevice(peer);
>          return err; <<<<<<<<<<<<<<<<<<<<<<<
> 
> err_register_peer:
>          free_netdev(peer);
>          return err;
> }
> 
> IMO the return must be removed to fall through the next label and free 
> the netdevice too.
> 
> Would you like so send a patch for veth.c too?

Ah, this is where Liu Dinghao got the veth suggestion :)

Does vxcan actually need this patch?

static void vxcan_setup(struct net_device *dev)
{
	[...]
        dev->needs_free_netdev  = true;