Re: [PATCH -next] irqchip/tango: Fix potential NULL pointer dereference

From: Marc Zyngier <marc.zyngier@arm.com>
To: YueHaibing <yuehaibing@huawei.com>
Cc: <tglx@linutronix.de>, <jason@lakedaemon.net>,
	<marc.w.gonzalez@free.fr>, <mans@mansr.com>,
	<linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH -next] irqchip/tango: Fix potential NULL pointer dereference
Date: Tue, 29 Jan 2019 08:55:41 +0000	[thread overview]
Message-ID: <86a7jjvo4y.wl-marc.zyngier@arm.com> (raw)
In-Reply-To: <20190129080122.20392-1-yuehaibing@huawei.com>

On Tue, 29 Jan 2019 08:01:22 +0000,
YueHaibing <yuehaibing@huawei.com> wrote:
> 
> There is a potential NULL pointer dereference in case kzalloc()
> fails and returns NULL.
> 
> Fixes: 4bba66899ac6 ("irqchip/tango: Add support for Sigma Designs SMP86xx/SMP87xx interrupt controller")
> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
> ---
>  drivers/irqchip/irq-tango.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/irqchip/irq-tango.c b/drivers/irqchip/irq-tango.c
> index ae28d86..a63b828 100644
> --- a/drivers/irqchip/irq-tango.c
> +++ b/drivers/irqchip/irq-tango.c
> @@ -191,6 +191,8 @@ static int __init tangox_irq_init(void __iomem *base, struct resource *baseres,
>  		panic("%pOFn: failed to get address", node);
>  
>  	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
> +	if (!chip)
> +		return -ENOMEM;
>  	chip->ctl = res.start - baseres->start;
>  	chip->base = base;
>  

This is a commendable effort, but given that the whole error handling
of this driver is just to simply panic, I have the ugly feeling that
this lack of check is more a feature than a bug... Not that I like it,
but at least it is consistent.

If you're going to change that, I'd recommend you overhaul the whole
thing.

Thanks,

	M.

-- 
Jazz is not dead, it just smell funny.