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From:   Charles Yi <be286@163.com>
To:     jikos@kernel.org, benjamin.tissoires@redhat.com
Cc:     linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        Charles Yi <be286@163.com>
Subject: [PATCH v2] HID: fix HID device resource race between HID core and debugging support
Date:   Tue,  7 Nov 2023 16:16:30 +0800
Message-Id: <20231107081630.34233-1-be286@163.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

hid_debug_events_release releases resources bound to the HID device
instance. hid_device_release releases the underlying HID device
instance potentially before hid_debug_events_release has completed
releasing debug resources bound to the same HID device instance.

Reference count to prevent the HID device instance from being torn
down preemptively when HID debugging support is used. When count
reaches zero, release core resources of HID device instance using
hid_hiddev_free.

The crash:
[  120.728477][ T4396] kernel BUG at lib/list_debug.c:53!
[  120.728505][ T4396] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
[  120.739806][ T4396] Modules linked in: bcmdhd dhd_static_buf 8822cu pcie_mhi r8168
[  120.747386][ T4396] CPU: 1 PID: 4396 Comm: hidt_bridge Not tainted 5.10.110 #257
[  120.754771][ T4396] Hardware name: Rockchip RK3588 EVB4 LP4 V10 Board (DT)
[  120.761643][ T4396] pstate: 60400089 (nZCv daIf +PAN -UAO -TCO BTYPE=--)
[  120.768338][ T4396] pc : __list_del_entry_valid+0x98/0xac
[  120.773730][ T4396] lr : __list_del_entry_valid+0x98/0xac
[  120.779120][ T4396] sp : ffffffc01e62bb60
[  120.783126][ T4396] x29: ffffffc01e62bb60 x28: ffffff818ce3a200
[  120.789126][ T4396] x27: 0000000000000009 x26: 0000000000980000
[  120.795126][ T4396] x25: ffffffc012431000 x24: ffffff802c6d4e00
[  120.801125][ T4396] x23: ffffff8005c66f00 x22: ffffffc01183b5b8
[  120.807125][ T4396] x21: ffffff819df2f100 x20: 0000000000000000
[  120.813124][ T4396] x19: ffffff802c3f0700 x18: ffffffc01d2cd058
[  120.819124][ T4396] x17: 0000000000000000 x16: 0000000000000000
[  120.825124][ T4396] x15: 0000000000000004 x14: 0000000000003fff
[  120.831123][ T4396] x13: ffffffc012085588 x12: 0000000000000003
[  120.837123][ T4396] x11: 00000000ffffbfff x10: 0000000000000003
[  120.843123][ T4396] x9 : 455103d46b329300 x8 : 455103d46b329300
[  120.849124][ T4396] x7 : 74707572726f6320 x6 : ffffffc0124b8cb5
[  120.855124][ T4396] x5 : ffffffffffffffff x4 : 0000000000000000
[  120.861123][ T4396] x3 : ffffffc011cf4f90 x2 : ffffff81fee7b948
[  120.867122][ T4396] x1 : ffffffc011cf4f90 x0 : 0000000000000054
[  120.873122][ T4396] Call trace:
[  120.876259][ T4396]  __list_del_entry_valid+0x98/0xac
[  120.881304][ T4396]  hid_debug_events_release+0x48/0x12c
[  120.886617][ T4396]  full_proxy_release+0x50/0xbc
[  120.891323][ T4396]  __fput+0xdc/0x238
[  120.895075][ T4396]  ____fput+0x14/0x24
[  120.898911][ T4396]  task_work_run+0x90/0x148
[  120.903268][ T4396]  do_exit+0x1bc/0x8a4
[  120.907193][ T4396]  do_group_exit+0x8c/0xa4
[  120.911458][ T4396]  get_signal+0x468/0x744
[  120.915643][ T4396]  do_signal+0x84/0x280
[  120.919650][ T4396]  do_notify_resume+0xd0/0x218
[  120.924262][ T4396]  work_pending+0xc/0x3f0

Fixes: cd667ce24796 ("HID: use debugfs for events/reports dumping")
Signed-off-by: Charles Yi <be286@163.com>
---
Changes in V2:
-The formatting of the "Fixes" tag
---
 drivers/hid/hid-core.c  | 12 ++++++++++--
 drivers/hid/hid-debug.c |  3 +++
 include/linux/hid.h     |  3 +++
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 8992e3c1e769..bd2f58e0e87a 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -702,15 +702,22 @@ static void hid_close_report(struct hid_device *device)
  * Free a device structure, all reports, and all fields.
  */
 
-static void hid_device_release(struct device *dev)
+void hid_hiddev_free(struct kref *ref)
 {
-	struct hid_device *hid = to_hid_device(dev);
+	struct hid_device *hid = container_of(ref, struct hid_device, ref);
 
 	hid_close_report(hid);
 	kfree(hid->dev_rdesc);
 	kfree(hid);
 }
 
+static void hid_device_release(struct device *dev)
+{
+	struct hid_device *hid = to_hid_device(dev);
+
+	kref_put(&hid->ref, hid_hiddev_free);
+}
+
 /*
  * Fetch a report description item from the data stream. We support long
  * items, though they are not used yet.
@@ -2846,6 +2853,7 @@ struct hid_device *hid_allocate_device(void)
 	spin_lock_init(&hdev->debug_list_lock);
 	sema_init(&hdev->driver_input_lock, 1);
 	mutex_init(&hdev->ll_open_lock);
+	kref_init(&hdev->ref);
 
 	hid_bpf_device_init(hdev);
 
diff --git a/drivers/hid/hid-debug.c b/drivers/hid/hid-debug.c
index e7ef1ea107c9..36c47012d79f 100644
--- a/drivers/hid/hid-debug.c
+++ b/drivers/hid/hid-debug.c
@@ -1135,6 +1135,7 @@ static int hid_debug_events_open(struct inode *inode, struct file *file)
 		goto out;
 	}
 	list->hdev = (struct hid_device *) inode->i_private;
+	kref_get(&list->hdev->ref);
 	file->private_data = list;
 	mutex_init(&list->read_mutex);
 
@@ -1227,6 +1228,8 @@ static int hid_debug_events_release(struct inode *inode, struct file *file)
 	list_del(&list->node);
 	spin_unlock_irqrestore(&list->hdev->debug_list_lock, flags);
 	kfifo_free(&list->hid_debug_fifo);
+
+	kref_put(&list->hdev->ref, hid_hiddev_free);
 	kfree(list);
 
 	return 0;
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 964ca1f15e3f..7867f571376c 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -679,6 +679,7 @@ struct hid_device {							/* device report descriptor */
 	struct list_head debug_list;
 	spinlock_t  debug_list_lock;
 	wait_queue_head_t debug_wait;
+	struct kref			ref;
 
 	unsigned int id;						/* system unique id */
 
@@ -687,6 +688,8 @@ struct hid_device {							/* device report descriptor */
 #endif /* CONFIG_BPF */
 };
 
+void hid_hiddev_free(struct kref *ref);
+
 #define to_hid_device(pdev) \
 	container_of(pdev, struct hid_device, dev)
 
-- 
2.34.1