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SubjectRe: [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@intel.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


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