linux-kernel - Re: [PATCH v2] usb: Use memdup

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Message-ID: <Pine.LNX.4.44L0.1512081021320.2050-100000@iolanthe.rowland.org>
Date:	Tue, 8 Dec 2015 10:23:07 -0500 (EST)
From:	Alan Stern <stern@...land.harvard.edu>
To:	"Pathak, Rahul (R.)" <rpathak@...teon.com>
cc:	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"kborer@...il.com" <kborer@...il.com>,
	"dan.carpenter@...cle.com" <dan.carpenter@...cle.com>,
	"chasemetzger15@...il.com" <chasemetzger15@...il.com>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] usb: Use memdup_user to reuse the code

On Tue, 8 Dec 2015, Pathak, Rahul (R.) wrote:

> From: Rahul Pathak <rpathak@...teon.com>
> 
> Fixing coccicheck warning which recommends to use memdup_user instead
> to reimplement its code, using memdup_user simplifies the code
> 
> ./drivers/usb/core/devio.c:1398:11-18: WARNING opportunity for memdup_user
> 
> Changes after v1: setting isopkt=NULL for proper kfree() call

This line belongs below the "---" tear line, so that it doesn't show up 
in the final commit changelog.  People reading the final commit won't 
care about earlier versions of the patch.

> Signed-off-by: Rahul Pathak <rpathak@...teon.com>
> ---
>  drivers/usb/core/devio.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
> index 38ae877c..844407c 100644
> --- a/drivers/usb/core/devio.c
> +++ b/drivers/usb/core/devio.c
> @@ -1395,11 +1395,10 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
>  		number_of_packets = uurb->number_of_packets;
>  		isofrmlen = sizeof(struct usbdevfs_iso_packet_desc) *
>  				   number_of_packets;
> -		isopkt = kmalloc(isofrmlen, GFP_KERNEL);
> -		if (!isopkt)
> -			return -ENOMEM;
> -		if (copy_from_user(isopkt, iso_frame_desc, isofrmlen)) {
> -			ret = -EFAULT;
> +		isopkt = memdup_user(iso_frame_desc, isofrmlen);
> +		if (IS_ERR(isopkt)) {
> +			ret = PTR_ERR(isopkt);
> +			isopkt = NULL;
>  			goto error;
>  		}
>  		for (totlen = u = 0; u < number_of_packets; u++) {

Aside from that,

Acked-by: Alan Stern <stern@...land.harvard.edu>

Alan Stern

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