diff mbox series

[v2,1/2] rpmsg: glink: Fix use-after-free in qcom_glink_rpdev_release()

Message ID 20211025163739.v2.1.Id19324ea36b4cf89faf98bf520bc6b6f01240433@changeid (mailing list archive)
State Superseded
Headers show
Series Fix two kernel warnings in glink driver | expand

Commit Message

Sujit Kautkar Oct. 25, 2021, 11:37 p.m. UTC
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@chromium.org>
---

(no changes since v1)

 drivers/rpmsg/qcom_glink_native.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

Matthias Kaehlcke Oct. 26, 2021, 12:29 a.m. UTC | #1
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@chromium.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
>
diff mbox series

Patch

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