linux-kernel - Re: [PATCH 1/2] lkdtm: fix memory leak of val

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Date:	Wed, 6 Apr 2016 15:53:13 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Sudip Mukherjee <sudipm.mukherjee@...il.com>
Cc:	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] lkdtm: fix memory leak of val

On Tue, Apr 5, 2016 at 10:11 AM, Sudip Mukherjee
<sudipm.mukherjee@...il.com> wrote:
> This case is supposed to read from a page after after it is freed, but
> it missed freeing val if we are not able to get a free page.
>
> Signed-off-by: Sudip Mukherjee <sudip.mukherjee@...ethink.co.uk>
> ---
>  drivers/misc/lkdtm.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/misc/lkdtm.c b/drivers/misc/lkdtm.c
> index 5f1a36b..2f0b022 100644
> --- a/drivers/misc/lkdtm.c
> +++ b/drivers/misc/lkdtm.c
> @@ -498,12 +498,13 @@ static void lkdtm_do_action(enum ctype which)
>         }
>         case CT_READ_BUDDY_AFTER_FREE: {
>                 unsigned long p = __get_free_page(GFP_KERNEL);
> -               int saw, *val = kmalloc(1024, GFP_KERNEL);
> +               int saw, *val;
>                 int *base;
>
>                 if (!p)
>                         break;
>
> +               val = kmalloc(1024, GFP_KERNEL);

There's actually still a leak of "p" here, but I've fix that now too. Thanks!

-Kees

>                 if (!val)
>                         break;
>
> --
> 1.9.1
>



-- 
Kees Cook
Chrome OS & Brillo Security