linux-kernel - Re: [PATCH] usb: fix potential integer overflow in usb_sg

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Date:	Mon, 18 Jan 2016 13:32:25 -0500 (EST)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Insu Yun <wuninsu@...il.com>
cc:	gregkh@...uxfoundation.org, <stefan.koch10@...il.com>,
	<kborer@...il.com>, <linux-usb@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <taesoo@...ech.edu>,
	<yeongjin.jang@...ech.edu>, <insu@...ech.edu>,
	<changwoo@...ech.edu>
Subject: Re: [PATCH] usb: fix potential integer overflow in usb_sg_init

On Mon, 18 Jan 2016, Insu Yun wrote:

> If nents value is sufficient large, e.g 0x40000000, 
> then it can overflow size in kmalloc and heap overflow happesns.
> Therefore nents value needs to be checked to prevent overflow.

I don't see why.  You seem to be assuming that failure with -EINVAL is 
better than failure with a heap overflow.  I disagree; a heap overflow 
provides more debugging information to help locate the reason for the 
underlying problem.

Alan Stern