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:   Mon, 25 Oct 2021 17:29:13 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Sujit Kautkar <sujitka@...omium.org>
Cc:     Andy Gross <agross@...nel.org>, Ohad Ben-Cohen <ohad@...ery.com>,
        Stephen Boyd <swboyd@...omium.org>,
        Sibi Sankar <sibis@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-remoteproc@...r.kernel.org
Subject: Re: [PATCH v2 1/2] rpmsg: glink: Fix use-after-free in
 qcom_glink_rpdev_release()

On Mon, Oct 25, 2021 at 04:37:52PM -0700, Sujit Kautkar wrote:
> qcom_glink_rpdev_release() sets channel->rpdev to NULL. However, with
> debug enabled kernel, qcom_glink_rpdev_release() gets delayed due to
> delayed kobject release and channel gets released by that time and
> triggers below kernel warning. To avoid this use-after-free, add a
> condition to checks if channel was already released.
> 
> | BUG: KASAN: use-after-free in qcom_glink_rpdev_release+0x54/0x70
> | Write of size 8 at addr ffffffaba438e8d0 by task kworker/6:1/54
> |
> | CPU: 6 PID: 54 Comm: kworker/6:1 Not tainted 5.4.109-lockdep #16
> | Hardware name: Google Lazor (rev3+) with KB Backlight (DT)
> | Workqueue: events kobject_delayed_cleanup
> | Call trace:
> |  dump_backtrace+0x0/0x284
> |  show_stack+0x20/0x2c
> |  dump_stack+0xd4/0x170
> |  print_address_description+0x3c/0x4a8
> |  __kasan_report+0x144/0x168
> |  kasan_report+0x10/0x18
> |  __asan_report_store8_noabort+0x1c/0x24
> |  qcom_glink_rpdev_release+0x54/0x70
> |  device_release+0x68/0x14c
> |  kobject_delayed_cleanup+0x158/0x2cc
> |  process_one_work+0x7cc/0x10a4
> |  worker_thread+0x80c/0xcec
> |  kthread+0x2a8/0x314
> |  ret_from_fork+0x10/0x18
> 
> Signed-off-by: Sujit Kautkar <sujitka@...omium.org>
> ---
> 
> (no changes since v1)
> 
>  drivers/rpmsg/qcom_glink_native.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> index e1444fefdd1c0..cc3556a9385a9 100644
> --- a/drivers/rpmsg/qcom_glink_native.c
> +++ b/drivers/rpmsg/qcom_glink_native.c
> @@ -270,6 +270,7 @@ static void qcom_glink_channel_release(struct kref *ref)
>  	spin_unlock_irqrestore(&channel->intent_lock, flags);
>  
>  	kfree(channel->name);
> +	channel = NULL;

This doesn't make much sense, 'channel' is a local variable, the only effect
this has is that the memory of 'channel' isn't freed by the 'kfree' below.

Maybe this is debug code and wasn't intended to be part of this patch?

>  	kfree(channel);
>  }
>  
> @@ -1372,8 +1373,10 @@ static void qcom_glink_rpdev_release(struct device *dev)
>  {
>  	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
>  	struct glink_channel *channel = to_glink_channel(rpdev->ept);
> +	if (channel) {
> +		channel->rpdev = NULL;
> +	}

Remove curly braces for single line branch.

>  
> -	channel->rpdev = NULL;
>  	kfree(rpdev);
>  }
>  
> -- 
> 2.31.0
> 

Powered by blists - more mailing lists