linux-kernel - Re: [PATCH 16/36] tty/vt: consolemap: check put_user() in con_get

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Message-ID: <8ad44d3b-449f-4a30-1a4c-dffd43bbbd1@linux.intel.com>
Date:   Tue, 7 Jun 2022 17:19:18 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Jiri Slaby <jslaby@...e.cz>
cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-serial <linux-serial@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 16/36] tty/vt: consolemap: check put_user() in
 con_get_unimap()

On Tue, 7 Jun 2022, Jiri Slaby wrote:

> Only the return value of copy_to_user() is checked in con_get_unimap().
> Do the same for put_user() of the count too.
> 
> Signed-off-by: Jiri Slaby <jslaby@...e.cz>
> ---
>  drivers/tty/vt/consolemap.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/vt/consolemap.c b/drivers/tty/vt/consolemap.c
> index 831450f2bfd1..92b5dddb00d9 100644
> --- a/drivers/tty/vt/consolemap.c
> +++ b/drivers/tty/vt/consolemap.c
> @@ -813,7 +813,8 @@ int con_get_unimap(struct vc_data *vc, ushort ct, ushort __user *uct,
>  	console_unlock();
>  	if (copy_to_user(list, unilist, min(ect, ct) * sizeof(*unilist)))
>  		ret = -EFAULT;
> -	put_user(ect, uct);
> +	if (put_user(ect, uct))
> +		ret = -EFAULT;
>  	kvfree(unilist);
>  	return ret ? ret : (ect <= ct) ? 0 : -ENOMEM;
>  }
> 

Doesn't this fix something?

-- 
 i.