linux-kernel - Re: [PATCH v4 4/6] phy: core: Fix an OF node refcount leakage in _of_phy

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Message-ID: <0699ed24-9603-48f5-b5bd-859dbed1da5c@icloud.com>
Date: Wed, 6 Nov 2024 23:28:37 +0800
From: Zijun Hu <zijun_hu@...oud.com>
To: Johan Hovold <johan@...nel.org>
Cc: Vinod Koul <vkoul@...nel.org>, Kishon Vijay Abraham I
 <kishon@...nel.org>, Felipe Balbi <balbi@...com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Rob Herring <robh@...nel.org>, Arnd Bergmann <arnd@...db.de>,
 Lee Jones <lee@...nel.org>, Lorenzo Pieralisi <lpieralisi@...nel.org>,
 Krzysztof Wilczyński <kw@...ux.com>,
 Bjorn Helgaas <bhelgaas@...gle.com>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Christophe JAILLET <christophe.jaillet@...adoo.fr>, stable@...r.kernel.org,
 linux-phy@...ts.infradead.org, linux-kernel@...r.kernel.org,
 Zijun Hu <quic_zijuhu@...cinc.com>
Subject: Re: [PATCH v4 4/6] phy: core: Fix an OF node refcount leakage in
 _of_phy_get()

On 2024/11/6 01:20, Johan Hovold wrote:
> On Sat, Nov 02, 2024 at 11:53:46AM +0800, Zijun Hu wrote:
>> From: Zijun Hu <quic_zijuhu@...cinc.com>
>>
>> _of_phy_get() will directly return when suffers of_device_is_compatible()
>> error, but it forgets to decrease refcount of OF node @args.np before error
>> return, the refcount was increased by previous of_parse_phandle_with_args()
>> so causes the OF node's refcount leakage.
>>
>> Fix by decreasing the refcount via of_node_put() before the error return.
>>
>> Fixes: b7563e2796f8 ("phy: work around 'phys' references to usb-nop-xceiv devices")
>> Cc: stable@...r.kernel.org
>> Signed-off-by: Zijun Hu <quic_zijuhu@...cinc.com>
>> ---
>>  drivers/phy/phy-core.c | 9 ++++++---
>>  1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
>> index 52ca590a58b9..3127c5d9c637 100644
>> --- a/drivers/phy/phy-core.c
>> +++ b/drivers/phy/phy-core.c
>> @@ -624,13 +624,15 @@ static struct phy *_of_phy_get(struct device_node *np, int index)
>>  	struct of_phandle_args args;
>>  
>>  	ret = of_parse_phandle_with_args(np, "phys", "#phy-cells",
>> -		index, &args);
>> +					 index, &args);
> 
> This is an unrelated change which do not belong in this patch (and even
> more so as it is a fix that is marked for backporting).
> 

make sense.
will remove it for next revision. (^^)

>>  	if (ret)
>>  		return ERR_PTR(-ENODEV);
>>  
>>  	/* This phy type handled by the usb-phy subsystem for now */
>> -	if (of_device_is_compatible(args.np, "usb-nop-xceiv"))
>> -		return ERR_PTR(-ENODEV);
>> +	if (of_device_is_compatible(args.np, "usb-nop-xceiv")) {
>> +		phy = ERR_PTR(-ENODEV);
>> +		goto out_put_node;
>> +	}
>>  
>>  	mutex_lock(&phy_provider_mutex);
>>  	phy_provider = of_phy_provider_lookup(args.np);
>> @@ -652,6 +654,7 @@ static struct phy *_of_phy_get(struct device_node *np, int index)
>>  
>>  out_unlock:
>>  	mutex_unlock(&phy_provider_mutex);
>> +out_put_node:
>>  	of_node_put(args.np);
>>  
>>  	return phy;A
> 
> With the above fixed:
> 
> Reviewed-by: Johan Hovold <johan+linaro@...nel.org>