linux-kernel - Re: [PATCH] mailbox: mailbox-test: set tdev->signal to NULL after freeing

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] [day] [month] [year] [list]

Date:	Mon, 6 Jun 2016 16:15:39 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Sudeep Holla <sudeep.holla@....com>
Cc:	Jassi Brar <jaswinder.singh@...aro.org>,
	linux-kernel@...r.kernel.org, Jassi Brar <jassisinghbrar@...il.com>
Subject: Re: [PATCH] mailbox: mailbox-test: set tdev->signal to NULL after
 freeing

On Tue, 24 May 2016, Sudeep Holla wrote:

> tdev->signal is not set NULL after it's freed. This will cause random
> exceptions when the stale pointer is accessed after tdev->signal is
> freed. Also, since tdev->signal allocation is skipped the next time
> it's written, this leads to continuous fault finally leading to the
> total death of the system.
> 
> Cc: Lee Jones <lee.jones@...aro.org>
> Cc: Jassi Brar <jassisinghbrar@...il.com>
> Fixes: d1c2f87c9a8f ("mailbox: mailbox-test: Prevent memory leak")
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
>  drivers/mailbox/mailbox-test.c | 1 +
>  1 file changed, 1 insertion(+)

Strange there isn't a kfree_and_null() call.

Patch looks okay to me though:

Acked-by: Lee Jones <lee.jones@...aro.org>

> diff --git a/drivers/mailbox/mailbox-test.c b/drivers/mailbox/mailbox-test.c
> index 58d04726cdd7..9ca96e9db6bf 100644
> --- a/drivers/mailbox/mailbox-test.c
> +++ b/drivers/mailbox/mailbox-test.c
> @@ -133,6 +133,7 @@ static ssize_t mbox_test_message_write(struct file *filp,
>  out:
>  	kfree(tdev->signal);
>  	kfree(tdev->message);
> +	tdev->signal = NULL;
> 
>  	return ret < 0 ? ret : count;
>  }

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog