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

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Message-ID: <adf9d668-0906-3004-d4e8-a7775844a985@datenfreihafen.org>
Date:   Tue, 26 Sep 2023 10:29:31 +0200
From:   Stefan Schmidt <stefan@...enfreihafen.org>
To:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Dinghao Liu <dinghao.liu@....edu.cn>
Cc:     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

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.

regards
Stefan Schmidt