netdev - Re: [patch] mdio_bus: NULL dereference on allocation error

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Message-ID: <20160112140647.GA5527@lunn.ch>
Date:	Tue, 12 Jan 2016 15:06:47 +0100
From:	Andrew Lunn <andrew@...n.ch>
To:	Dan Carpenter <dan.carpenter@...cle.com>
Cc:	Florian Fainelli <f.fainelli@...il.com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [patch] mdio_bus: NULL dereference on allocation error

On Tue, Jan 12, 2016 at 12:34:36PM +0300, Dan Carpenter wrote:
> If bus = kzalloc() fails then we end up dereferencing bus when we do
> "bus->irq[i] = PHY_POLL;".  The code is a little simpler if we reverse
> the NULL check and return directly on failure.
> 
> Fixes: e7f4dc3536a4 ('mdio: Move allocation of interrupts into core')
> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>

Reviewed-by: Andrew Lunn <andrew@...n.ch>

Thanks
	Andrew

> 
> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
> index 0be7b3d..0cba64f 100644
> --- a/drivers/net/phy/mdio_bus.c
> +++ b/drivers/net/phy/mdio_bus.c
> @@ -102,11 +102,12 @@ struct mii_bus *mdiobus_alloc_size(size_t size)
>  		alloc_size = sizeof(*bus);
>  
>  	bus = kzalloc(alloc_size, GFP_KERNEL);
> -	if (bus) {
> -		bus->state = MDIOBUS_ALLOCATED;
> -		if (size)
> -			bus->priv = (void *)bus + aligned_size;
> -	}
> +	if (!bus)
> +		return NULL;
> +
> +	bus->state = MDIOBUS_ALLOCATED;
> +	if (size)
> +		bus->priv = (void *)bus + aligned_size;
>  
>  	/* Initialise the interrupts to polling */
>  	for (i = 0; i < PHY_MAX_ADDR; i++)