linux-kernel - Re: [char-misc-next 2/8] mei: hbm: validate client index is not exceeding allocated array size

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 29 Oct 2013 16:19:45 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Tomas Winkler <tomas.winkler@...el.com>
Cc:	arnd@...db.de, linux-kernel@...r.kernel.org
Subject: Re: [char-misc-next 2/8] mei: hbm: validate client index is not
 exceeding allocated array size

On Mon, Oct 21, 2013 at 10:05:37PM +0300, Tomas Winkler wrote:
> Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
> ---
>  drivers/misc/mei/hbm.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/misc/mei/hbm.c b/drivers/misc/mei/hbm.c
> index 9b3a0fb..0f5e8ca 100644
> --- a/drivers/misc/mei/hbm.c
> +++ b/drivers/misc/mei/hbm.c
> @@ -228,8 +228,6 @@ static int mei_hbm_prop_req(struct mei_device *dev)
>  	unsigned long client_num;
>  
>  
> -	client_num = dev->me_client_presentation_num;
> -
>  	next_client_index = find_next_bit(dev->me_clients_map, MEI_CLIENTS_MAX,
>  					  dev->me_client_index);
>  
> @@ -241,6 +239,10 @@ static int mei_hbm_prop_req(struct mei_device *dev)
>  		return 0;
>  	}
>  
> +	client_num = dev->me_client_presentation_num;
> +	if (WARN_ON(dev->me_clients_num <= client_num))
> +		return -EIO;

How can this happen?  Why is spitting out a huge warning in the syslog
going to help anything?  If a user can do this, then great, now you can
DoS your syslog :(

If a user can't do this, then why tell them, it's your driver's bug that
you should just fix.

greg k-h
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/