linux-kernel - Re: [PATCH] staging: ft1000: Copy from user into correct data

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Date:	Fri, 12 Nov 2010 11:14:26 +0100
From:	Belisko Marek <marek.belisko@...il.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	LKML <linux-kernel@...r.kernel.org>, Greg KH <greg@...ah.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] staging: ft1000: Copy from user into correct data

Hi Steven,

On Thu, Nov 11, 2010 at 5:29 PM, Steven Rostedt <rostedt@...dmis.org> wrote:
> While doing a ktest.pl I used a MIN_CONFIG that had STAGING enabled, and
> a randconfig with CONFIG_DEBUG_STRICT_USER_COPY_CHECKS enabled caught
> the following bug:
>
> In file included from /home/rostedt/work/autotest/nobackup/linux-test.git/arch/x86/include/asm/uaccess.h:571:0,
>                 from /home/rostedt/work/autotest/nobackup/linux-test.git/include/linux/poll.h:14,
>                 from /home/rostedt/work/autotest/nobackup/linux-test.git/drivers/staging/ft1000/ft1000-usb/ft1000_chdev.c:32:
> In function 'copy_from_user',
>    inlined from 'ft1000_ChIoctl' at /home/rostedt/work/autotest/nobackup/linux-test.git/drivers/staging/ft1000/ft1000-usb/ft1000_chdev.c:702:36:
> /home/rostedt/work/autotest/nobackup/linux-test.git/arch/x86/include/asm/uaccess_32.h:212:26: error: call to 'copy_from_user_overflow' declared with attribute error: copy_from_user() buffer size is not provably correct
>
>
> Looking at the code it was obvious what the problem was. The pointer
> dpram_data was being allocated but the address was being written to.
> Looking at the comment above the code shows that it use to write into an
> element of that pointer where the '&' is appropriate. But now that it
> writes to the pointer itself, we need to remove the '&' otherwise we
> write over the pointer and not into the data it points to.
Good catch but anyway this interface is removed. Already send patches to Greg-KH
but there was some patch problem so they're not applied to next yet.
Thanks for effort.
>
> Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
>
> diff --git a/drivers/staging/ft1000/ft1000-usb/ft1000_chdev.c b/drivers/staging/ft1000/ft1000-usb/ft1000_chdev.c
> index 87a6487..8e8197d 100644
> --- a/drivers/staging/ft1000/ft1000-usb/ft1000_chdev.c
> +++ b/drivers/staging/ft1000/ft1000-usb/ft1000_chdev.c
> @@ -699,7 +699,7 @@ static long ft1000_ChIoctl (struct file *File, unsigned int Command,
>                        break;
>
>                 //if ( copy_from_user(&(dpram_command.dpram_blk), (PIOCTL_DPRAM_BLK)Argument, msgsz+2) ) {
> -                if ( copy_from_user(&dpram_data, argp, msgsz+2) ) {
> +                if ( copy_from_user(dpram_data, argp, msgsz+2) ) {
>                     DEBUG("FT1000:ft1000_ChIoctl: copy fault occurred\n");
>                     result = -EFAULT;
>                 }
>
>
>

thanks,

marek

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