From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
To: Julia Lawall <julia.lawall@lip6.fr>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Kishon Vijay Abraham I <kishon@ti.com>,
"Sergei Shtylyov (sergei.shtylyov@cogentembedded.com)"
<sergei.shtylyov@cogentembedded.com>
Subject: RE: question about drivers/phy/renesas/phy-rcar-gen2.c
Date: Wed, 27 Feb 2019 01:06:25 +0000 [thread overview]
Message-ID: <TY2PR01MB481259F0AFBF6DEF9565792CD8740@TY2PR01MB4812.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1902261000420.3499@hadrien>
Hello,
> From: Julia Lawall, Sent: Tuesday, February 26, 2019 6:01 PM
>
> On Tue, 26 Feb 2019, Yoshihiro Shimoda wrote:
>
> > Hello,
> > (Sergei made this code, so I added his email as CC)
> >
> > I'm sorry for the delayed response.
> >
> > > From: Julia Lawall, Sent: Sunday, February 3, 2019 4:03 PM
> > >
> > > Hello,
> > >
> > > I was wondering whether phy-rcar-gen2.c would use dynamically allocated
> > > device nodes?
> >
> > I'm sorry, but what is "dynamically allocated device nodes"?
>
> Device nodes for which there will be a meor leak if one doesn't put
> of_node_put.
Thank you. I understood it.
> julia
>
> >
> > Best regards,
> > Yoshihiro Shimoda
> >
> > > If so, it looks like the following code could cause a
> > > use-after-free, due to not incrementing th reference count:
> > >
> > > for_each_child_of_node(dev->of_node, np) {
> > > struct rcar_gen2_channel *channel = drv->channels + i;
> > > u32 channel_num;
> > > int error, n;
> > >
> > > channel->of_node = np;
IIUC, since the channel->of_node will be used for comparing the pointer
in rcar_gen2_phy_xlate(), it is not use-after-free.
However, the for_each_child_of_node() in rcar_gen2_phy_probe() will return
without of_put_node() at error paths. So, I'll submit a bugfix patch later.
Thank you very much for your report!
Best regards,
Yoshihiro Shimoda
> > > ...
> > > }
> > >
> > > On the other hand, if the reference cound it incrememnted, preventing
> > > memory leaks in the case where the probe function fails would entail some
> > > complex rewriting of the code, so I thought it would be better to ask
> > > first.
> > >
> > > thanks,
> > > julia
> >
next prev parent reply other threads:[~2019-02-27 1:06 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-03 7:02 question about drivers/phy/renesas/phy-rcar-gen2.c Julia Lawall
2019-02-26 8:54 ` Yoshihiro Shimoda
2019-02-26 9:01 ` Julia Lawall
2019-02-27 1:06 ` Yoshihiro Shimoda [this message]
2019-02-27 6:08 ` Julia Lawall
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