Re: [PATCH v2 4/6] phy: core: Fix an OF node refcount leakage in _of_phy_get()

From: Johan Hovold <johan@kernel.org>
To: Zijun Hu <zijun_hu@icloud.com>
Cc: "Vinod Koul" <vkoul@kernel.org>,
	"Kishon Vijay Abraham I" <kishon@kernel.org>,
	"Felipe Balbi" <balbi@ti.com>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Rob Herring" <robh@kernel.org>, "Arnd Bergmann" <arnd@arndb.de>,
	"Lee Jones" <lee@kernel.org>,
	"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
	"Krzysztof Wilczyński" <kw@linux.com>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"David S. Miller" <davem@davemloft.net>,
	"Eric Dumazet" <edumazet@google.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Christophe JAILLET" <christophe.jaillet@wanadoo.fr>,
	stable@vger.kernel.org, linux-phy@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	"Zijun Hu" <quic_zijuhu@quicinc.com>
Subject: Re: [PATCH v2 4/6] phy: core: Fix an OF node refcount leakage in _of_phy_get()
Date: Tue, 29 Oct 2024 14:47:31 +0100	[thread overview]
Message-ID: <ZyDnc7HpMTnwEs-2@hovoldconsulting.com> (raw)
In-Reply-To: <20241024-phy_core_fix-v2-4-fc0c63dbfcf3@quicinc.com>

On Thu, Oct 24, 2024 at 10:39:29PM +0800, Zijun Hu wrote:
> From: Zijun Hu <quic_zijuhu@quicinc.com>
> 
> It will leak refcount of OF node @args.np for _of_phy_get() not to
> decrease refcount increased by previous of_parse_phandle_with_args()
> when returns due to of_device_is_compatible() error.
> 
> Fix by adding of_node_put() before the error return.
> 
> Fixes: b7563e2796f8 ("phy: work around 'phys' references to usb-nop-xceiv devices")
> Cc: stable@vger.kernel.org
> Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
> ---
>  drivers/phy/phy-core.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
> index 52ca590a58b9..967878b78797 100644
> --- a/drivers/phy/phy-core.c
> +++ b/drivers/phy/phy-core.c
> @@ -629,8 +629,11 @@ static struct phy *_of_phy_get(struct device_node *np, int index)
>  		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"))
> +	if (of_device_is_compatible(args.np, "usb-nop-xceiv")) {
> +		/* Put refcount above of_parse_phandle_with_args() got */

No need for a comment as this is already handled in the later paths.

> +		of_node_put(args.np);

For that reason you should probably initialise ret and add a new label
out_put_node that you jump to here instead.

>  		return ERR_PTR(-ENODEV);
> +	}
>  
>  	mutex_lock(&phy_provider_mutex);
>  	phy_provider = of_phy_provider_lookup(args.np);

Johan

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