* [PATCH v3 0/2] Fix two kernel warnings in glink driver
@ 2021-11-02 23:51 Sujit Kautkar
2021-11-02 23:51 ` [PATCH v3 1/2] rpmsg: glink: Fix use-after-free in qcom_glink_rpdev_release() Sujit Kautkar
0 siblings, 1 reply; 3+ messages in thread
From: Sujit Kautkar @ 2021-11-02 23:51 UTC (permalink / raw)
To: Andy Gross, Ohad Ben-Cohen
Cc: Bjorn Andersson, Sibi Sankar, Matthias Kaehlcke, Stephen Boyd,
Sujit Kautkar, linux-arm-msm, linux-kernel, linux-remoteproc
These changes addresses kernel warnings which shows up after enabling
debug kernel. First one fixes use-after-free warning and second fixes
warning by updating cdev APIs
Changes in v3:
- Clear ept pointers in patch 1
- Remove error check in patch 2
Changes in v2:
- Fix typo in commit message
Sujit Kautkar (2):
rpmsg: glink: Fix use-after-free in qcom_glink_rpdev_release()
rpmsg: glink: Update cdev add/del API in
rpmsg_ctrldev_release_device()
drivers/rpmsg/qcom_glink_native.c | 12 ++++++++++--
drivers/rpmsg/rpmsg_char.c | 10 ++--------
2 files changed, 12 insertions(+), 10 deletions(-)
--
2.31.0
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH v3 1/2] rpmsg: glink: Fix use-after-free in qcom_glink_rpdev_release()
2021-11-02 23:51 [PATCH v3 0/2] Fix two kernel warnings in glink driver Sujit Kautkar
@ 2021-11-02 23:51 ` Sujit Kautkar
2021-11-03 16:34 ` Matthias Kaehlcke
0 siblings, 1 reply; 3+ messages in thread
From: Sujit Kautkar @ 2021-11-02 23:51 UTC (permalink / raw)
To: Andy Gross, Ohad Ben-Cohen
Cc: Bjorn Andersson, Sibi Sankar, Matthias Kaehlcke, Stephen Boyd,
Sujit Kautkar, linux-arm-msm, linux-kernel, linux-remoteproc
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, clear ept
pointers during ept destroy and channel release and add a new condition
in qcom_glink_rpdev_release() to access channel
| 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>
---
Changes in v3:
- Clear ept pointers and add extra conditions
Changes in v2:
- Fix typo in commit message
drivers/rpmsg/qcom_glink_native.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
index e1444fefdd1c0..0c64a6f7a4f09 100644
--- a/drivers/rpmsg/qcom_glink_native.c
+++ b/drivers/rpmsg/qcom_glink_native.c
@@ -269,6 +269,9 @@ static void qcom_glink_channel_release(struct kref *ref)
idr_destroy(&channel->riids);
spin_unlock_irqrestore(&channel->intent_lock, flags);
+ if (channel->rpdev)
+ channel->rpdev->ept = NULL;
+
kfree(channel->name);
kfree(channel);
}
@@ -1214,6 +1217,8 @@ static void qcom_glink_destroy_ept(struct rpmsg_endpoint *ept)
channel->ept.cb = NULL;
spin_unlock_irqrestore(&channel->recv_lock, flags);
+ channel->rpdev->ept = NULL;
+
/* Decouple the potential rpdev from the channel */
channel->rpdev = NULL;
@@ -1371,9 +1376,12 @@ static const struct rpmsg_endpoint_ops glink_endpoint_ops = {
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);
+ struct glink_channel *channel = NULL;
- channel->rpdev = NULL;
+ if (rpdev->ept) {
+ channel = to_glink_channel(rpdev->ept);
+ channel->rpdev = NULL;
+ }
kfree(rpdev);
}
--
2.31.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v3 1/2] rpmsg: glink: Fix use-after-free in qcom_glink_rpdev_release()
2021-11-02 23:51 ` [PATCH v3 1/2] rpmsg: glink: Fix use-after-free in qcom_glink_rpdev_release() Sujit Kautkar
@ 2021-11-03 16:34 ` Matthias Kaehlcke
0 siblings, 0 replies; 3+ messages in thread
From: Matthias Kaehlcke @ 2021-11-03 16:34 UTC (permalink / raw)
To: Sujit Kautkar
Cc: Andy Gross, Ohad Ben-Cohen, Bjorn Andersson, Sibi Sankar,
Stephen Boyd, linux-arm-msm, linux-kernel, linux-remoteproc
Hi Sujit,
On Tue, Nov 02, 2021 at 04:51:49PM -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, clear ept
> pointers during ept destroy and channel release and add a new condition
> in qcom_glink_rpdev_release() to access channel
>
> | 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>
> ---
> Changes in v3:
> - Clear ept pointers and add extra conditions
>
> Changes in v2:
> - Fix typo in commit message
>
> drivers/rpmsg/qcom_glink_native.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> index e1444fefdd1c0..0c64a6f7a4f09 100644
> --- a/drivers/rpmsg/qcom_glink_native.c
> +++ b/drivers/rpmsg/qcom_glink_native.c
> @@ -269,6 +269,9 @@ static void qcom_glink_channel_release(struct kref *ref)
> idr_destroy(&channel->riids);
> spin_unlock_irqrestore(&channel->intent_lock, flags);
>
> + if (channel->rpdev)
> + channel->rpdev->ept = NULL;
> +
> kfree(channel->name);
> kfree(channel);
> }
> @@ -1214,6 +1217,8 @@ static void qcom_glink_destroy_ept(struct rpmsg_endpoint *ept)
> channel->ept.cb = NULL;
> spin_unlock_irqrestore(&channel->recv_lock, flags);
>
> + channel->rpdev->ept = NULL;
> +
> /* Decouple the potential rpdev from the channel */
> channel->rpdev = NULL;
>
> @@ -1371,9 +1376,12 @@ static const struct rpmsg_endpoint_ops glink_endpoint_ops = {
> 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);
> + struct glink_channel *channel = NULL;
no need to initialize the pointer, it is assigned in the path that uses it.
>
> - channel->rpdev = NULL;
> + if (rpdev->ept) {
> + channel = to_glink_channel(rpdev->ept);
> + channel->rpdev = NULL;
> + }
> kfree(rpdev);
> }
Looks like this is already fixed in -next by:
commit 343ba27b6f9d473ec3e602cc648300eb03a7fa05
Author: Chris Lew <clew@codeaurora.org>
Date: Thu Jul 30 10:48:15 2020 +0530
rpmsg: glink: Remove channel decouple from rpdev release
If a channel is being rapidly restarting and the kobj release worker is
busy, there is a chance the rpdev_release function will run after the
channel struct itself has been released.
There should not be a need to decouple the channel from rpdev in the
rpdev release since that should only happen from the close commands.
Signed-off-by: Chris Lew <clew@codeaurora.org>
Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/1596086296-28529-6-git-send-email-deesin@codeaurora.org
^ permalink raw reply [flat|nested] 3+ messages in thread
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