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
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 | 5 ++++-
drivers/rpmsg/rpmsg_char.c | 5 ++---
2 files changed, 6 insertions(+), 4 deletions(-)
--
2.31.0
From: Sujit Kautkar <[email protected]>
Replace cdev add/del APIs with cdev_device_add/cdev_device_del to avoid
below kernel warning. This correctly takes a reference to the parent
device so the parent will not get released until all references to the
cdev are released.
| ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x7c
| WARNING: CPU: 7 PID: 19892 at lib/debugobjects.c:488 debug_print_object+0x13c/0x1b0
| CPU: 7 PID: 19892 Comm: kworker/7:4 Tainted: G W 5.4.147-lockdep #1
| ==================================================================
| Hardware name: Google CoachZ (rev1 - 2) with LTE (DT)
| Workqueue: events kobject_delayed_cleanup
| pstate: 60c00009 (nZCv daif +PAN +UAO)
| pc : debug_print_object+0x13c/0x1b0
| lr : debug_print_object+0x13c/0x1b0
| sp : ffffff83b2ec7970
| x29: ffffff83b2ec7970 x28: dfffffd000000000
| x27: ffffff83d674f000 x26: dfffffd000000000
| x25: ffffffd06b8fa660 x24: dfffffd000000000
| x23: 0000000000000000 x22: ffffffd06b7c5108
| x21: ffffffd06d597860 x20: ffffffd06e2c21c0
| x19: ffffffd06d5974c0 x18: 000000000001dad8
| x17: 0000000000000000 x16: dfffffd000000000
| BUG: KASAN: use-after-free in qcom_glink_rpdev_release+0x54/0x70
| x15: ffffffffffffffff x14: 79616c6564203a74
| x13: 0000000000000000 x12: 0000000000000080
| Write of size 8 at addr ffffff83d95768d0 by task kworker/3:1/150
| x11: 0000000000000001 x10: 0000000000000000
| x9 : fc9e8edec0ad0300 x8 : fc9e8edec0ad0300
|
| x7 : 0000000000000000 x6 : 0000000000000000
| x5 : 0000000000000080 x4 : 0000000000000000
| CPU: 3 PID: 150 Comm: kworker/3:1 Tainted: G W 5.4.147-lockdep #1
| x3 : ffffffd06c149574 x2 : ffffff83f77f7498
| x1 : ffffffd06d596f60 x0 : 0000000000000061
| Hardware name: Google CoachZ (rev1 - 2) with LTE (DT)
| Call trace:
| debug_print_object+0x13c/0x1b0
| Workqueue: events kobject_delayed_cleanup
| __debug_check_no_obj_freed+0x25c/0x3c0
| debug_check_no_obj_freed+0x18/0x20
| Call trace:
| slab_free_freelist_hook+0xb4/0x1bc
| kfree+0xe8/0x2d8
| dump_backtrace+0x0/0x27c
| rpmsg_ctrldev_release_device+0x78/0xb8
| device_release+0x68/0x14c
| show_stack+0x20/0x2c
| kobject_cleanup+0x12c/0x298
| kobject_delayed_cleanup+0x10/0x18
| dump_stack+0xe0/0x19c
| process_one_work+0x578/0x92c
| worker_thread+0x804/0xcf8
| print_address_description+0x3c/0x4a8
| kthread+0x2a8/0x314
| ret_from_fork+0x10/0x18
| __kasan_report+0x100/0x124
Signed-off-by: Sujit Kautkar <[email protected]>
---
drivers/rpmsg/rpmsg_char.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index 876ce43df732b..b63a5c396da57 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -458,7 +458,7 @@ static void rpmsg_ctrldev_release_device(struct device *dev)
ida_simple_remove(&rpmsg_ctrl_ida, dev->id);
ida_simple_remove(&rpmsg_minor_ida, MINOR(dev->devt));
- cdev_del(&ctrldev->cdev);
+ cdev_device_del(&ctrldev->cdev, &ctrldev->dev);
kfree(ctrldev);
}
@@ -493,14 +493,13 @@ static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
dev->id = ret;
dev_set_name(&ctrldev->dev, "rpmsg_ctrl%d", ret);
- ret = cdev_add(&ctrldev->cdev, dev->devt, 1);
+ ret = cdev_device_add(&ctrldev->cdev, &ctrldev->dev);
if (ret)
goto free_ctrl_ida;
/* We can now rely on the release function for cleanup */
dev->release = rpmsg_ctrldev_release_device;
- ret = device_add(dev);
if (ret) {
dev_err(&rpdev->dev, "device_add failed: %d\n", ret);
put_device(dev);
--
2.31.0
From: Sujit Kautkar <[email protected]>
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 <[email protected]>
---
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;
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);
}
--
2.31.0