linux-kernel - Re: [PATCH] [v2] ieee802154: ca8210: Fix a potential UAF in ca8210

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Message-ID: <CAK-6q+gfN7GtwfpUvOjNsNE9LSMTGrdLE6+-dgUEkVaA6SK1zw@mail.gmail.com>
Date:   Tue, 26 Sep 2023 12:40:51 -0400
From:   Alexander Aring <aahringo@...hat.com>
To:     Stefan Schmidt <stefan@...enfreihafen.org>
Cc:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Dinghao Liu <dinghao.liu@....edu.cn>,
        Alexander Aring <alex.aring@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Marcel Holtmann <marcel@...tmann.org>,
        Harry Morris <harrymorris12@...il.com>,
        linux-wpan@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [v2] ieee802154: ca8210: Fix a potential UAF in ca8210_probe

Hi,

On Tue, Sep 26, 2023 at 4:29 AM Stefan Schmidt
<stefan@...enfreihafen.org> wrote:
>
> Hello.
>
> On 26.09.23 10:02, Miquel Raynal wrote:
> > Hi Dinghao,
> >
> > dinghao.liu@....edu.cn wrote on Tue, 26 Sep 2023 11:22:44 +0800:
> >
> >> If of_clk_add_provider() fails in ca8210_register_ext_clock(),
> >> it calls clk_unregister() to release priv->clk and returns an
> >> error. However, the caller ca8210_probe() then calls ca8210_remove(),
> >> where priv->clk is freed again in ca8210_unregister_ext_clock(). In
> >> this case, a use-after-free may happen in the second time we call
> >> clk_unregister().
> >>
> >> Fix this by removing the first clk_unregister(). Also, priv->clk could
> >> be an error code on failure of clk_register_fixed_rate(). Use
> >> IS_ERR_OR_NULL to catch this case in ca8210_unregister_ext_clock().
> >>
> >> Fixes: ded845a781a5 ("ieee802154: Add CA8210 IEEE 802.15.4 device driver")
> >
> > Missing Cc stable, this needs to be backported.
> >
> >> Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
> >> ---
> >>
> >> Changelog:
> >>
> >> v2: -Remove the first clk_unregister() instead of nulling priv->clk.
> >> ---
> >>   drivers/net/ieee802154/ca8210.c | 3 +--
> >>   1 file changed, 1 insertion(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/net/ieee802154/ca8210.c b/drivers/net/ieee802154/ca8210.c
> >> index aebb19f1b3a4..b35c6f59bd1a 100644
> >> --- a/drivers/net/ieee802154/ca8210.c
> >> +++ b/drivers/net/ieee802154/ca8210.c
> >> @@ -2759,7 +2759,6 @@ static int ca8210_register_ext_clock(struct spi_device *spi)
> >>      }
> >>      ret = of_clk_add_provider(np, of_clk_src_simple_get, priv->clk);
> >>      if (ret) {
> >> -            clk_unregister(priv->clk);
> >>              dev_crit(
> >>                      &spi->dev,
> >>                      "Failed to register external clock as clock provider\n"
> >
> > I was hoping you would simplify this function a bit more.
> >
> >> @@ -2780,7 +2779,7 @@ static void ca8210_unregister_ext_clock(struct spi_device *spi)
> >>   {
> >>      struct ca8210_priv *priv = spi_get_drvdata(spi);
> >>
> >> -    if (!priv->clk)
> >> +    if (IS_ERR_OR_NULL(priv->clk))
> >>              return
> >>
> >>      of_clk_del_provider(spi->dev.of_node);
> >
> > Alex, Stefan, who handles wpan and wpan/next this release?
>
> IIRC it would be me for wpan and Alex for wpan-next.

That's okay for me.

- Alex