linux-kernel - Re: [PATCH][next] soc: fsl: dpio: fix dereference of pointer p before null check

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Date:   Mon, 24 Feb 2020 09:35:29 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Colin King <colin.king@...onical.com>
Cc:     Roy Pledge <Roy.Pledge@....com>, Li Yang <leoyang.li@....com>,
        Youri Querry <youri.querry_1@....com>,
        linuxppc-dev@...ts.ozlabs.org,
        linux-arm-kernel@...ts.infradead.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] soc: fsl: dpio: fix dereference of pointer p
 before null check

On Fri, Feb 21, 2020 at 11:11:43PM +0000, Colin King wrote:
> ---
>  drivers/soc/fsl/dpio/qbman-portal.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/soc/fsl/dpio/qbman-portal.c b/drivers/soc/fsl/dpio/qbman-portal.c
> index 740ee0d19582..d1f49caa5b13 100644
> --- a/drivers/soc/fsl/dpio/qbman-portal.c
> +++ b/drivers/soc/fsl/dpio/qbman-portal.c
> @@ -249,10 +249,11 @@ struct qbman_swp *qbman_swp_init(const struct qbman_swp_desc *d)
>  	u32 mask_size;
>  	u32 eqcr_pi;
>  
> -	spin_lock_init(&p->access_spinlock);
> -
>  	if (!p)
>  		return NULL;
> +
> +	spin_lock_init(&p->access_spinlock);

Allocations in the declaration blog are not super common in the kernel,
but they're more bug prone.  Generally, it's not beautiful to call a
function which can fail in the allocation block.

regards,
dan carpenter