linux-kernel - Re: [PATCH] rpmsg: virtio_rpmsg

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Message-ID: <1cc3d697-6fde-901b-2e35-2e2b53b44425@ti.com>
Date:   Mon, 12 Aug 2019 11:47:58 -0400
From:   "Andrew F. Davis" <afd@...com>
To:     Suman Anna <s-anna@...com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
CC:     <linux-remoteproc@...r.kernel.org>,
        Loic Pallardy <loic.pallardy@...com>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] rpmsg: virtio_rpmsg_bus: replace "%p" with "%pK"

On 10/23/18 9:19 PM, Suman Anna wrote:
> The virtio_rpmsg_bus driver uses the "%p" format-specifier for
> printing the vring buffer address. This prints only a hashed
> pointer even for previliged users. Use "%pK" instead so that
> the address can be printed during debug using kptr_restrict
> sysctl.
> 


s/previliged/privileged

You describe what the code does, but not why you need this. %pK is used
for only about 1% of pointer printing, why do you want to leak this
address to userspace at all?

Andrew


> Signed-off-by: Suman Anna <s-anna@...com>
> ---
>  drivers/rpmsg/virtio_rpmsg_bus.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
> index f29dee731026..1345f373a1a0 100644
> --- a/drivers/rpmsg/virtio_rpmsg_bus.c
> +++ b/drivers/rpmsg/virtio_rpmsg_bus.c
> @@ -950,7 +950,7 @@ static int rpmsg_probe(struct virtio_device *vdev)
>  		goto vqs_del;
>  	}
>  
> -	dev_dbg(&vdev->dev, "buffers: va %p, dma %pad\n",
> +	dev_dbg(&vdev->dev, "buffers: va %pK, dma %pad\n",
>  		bufs_va, &vrp->bufs_dma);
>  
>  	/* half of the buffers is dedicated for RX */
>