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Message-ID: <20201205131928.7d5c8e59@kicinski-fedora-pc1c0hjn.DHCP.thefacebook.com>
Date: Sat, 5 Dec 2020 13:19:28 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: Rasmus Villemoes <rasmus.villemoes@...vas.dk>
Cc: Li Yang <leoyang.li@....com>,
"David S. Miller" <davem@...emloft.net>,
Zhao Qiang <qiang.zhao@....com>,
Vladimir Oltean <vladimir.oltean@....com>,
netdev@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 11/20] ethernet: ucc_geth: fix use-after-free in
ucc_geth_remove()
On Sat, 5 Dec 2020 22:04:28 +0100 Rasmus Villemoes wrote:
> On 05/12/2020 21.48, Jakub Kicinski wrote:
> > On Sat, 5 Dec 2020 20:17:34 +0100 Rasmus Villemoes wrote:
> >> - unregister_netdev(dev);
> >> - free_netdev(dev);
> >> ucc_geth_memclean(ugeth);
> >> if (of_phy_is_fixed_link(np))
> >> of_phy_deregister_fixed_link(np);
> >> of_node_put(ugeth->ug_info->tbi_node);
> >> of_node_put(ugeth->ug_info->phy_node);
> >> + unregister_netdev(dev);
> >> + free_netdev(dev);
> >
> > Are you sure you want to move the unregister_netdev() as well as the
> > free?
>
> Hm, dunno, I don't think it's needed per se, but it also shouldn't hurt
> from what I can tell. It seems more natural that they go together, but
> if you prefer a minimal patch that's of course also possible.
I was concerned about the fact that we free things and release
references while the device may still be up (given that it's
unregister_netdev() that will take it down).
> I only noticed because I needed to add a free of the ug_info in a later
> patch.
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