[PATCH v1] Bluetooth: btusb: mediatek: Fix kernel crash when releasing mtk iso interface

[Chris Lu <chris.lu@mediatek.com>]

When performing reset tests and encountering abnormal card drop issues
that lead to a kernel crash, it is necessary to perform a null check
before releasing resources to avoid attempting to release a null pointer.

<4>[   29.158070] Hardware name: Google Quigon sku196612/196613 board (DT)
<4>[   29.158076] Workqueue: hci0 hci_cmd_sync_work [bluetooth]
<4>[   29.158154] pstate: 20400009 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
<4>[   29.158162] pc : klist_remove+0x90/0x158
<4>[   29.158174] lr : klist_remove+0x88/0x158
<4>[   29.158180] sp : ffffffc0846b3c00
<4>[   29.158185] pmr_save: 000000e0
<4>[   29.158188] x29: ffffffc0846b3c30 x28: ffffff80cd31f880 x27: ffffff80c1bdc058
<4>[   29.158199] x26: dead000000000100 x25: ffffffdbdc624ea3 x24: ffffff80c1bdc4c0
<4>[   29.158209] x23: ffffffdbdc62a3e6 x22: ffffff80c6c07000 x21: ffffffdbdc829290
<4>[   29.158219] x20: 0000000000000000 x19: ffffff80cd3e0648 x18: 000000031ec97781
<4>[   29.158229] x17: ffffff80c1bdc4a8 x16: ffffffdc10576548 x15: ffffff80c1180428
<4>[   29.158238] x14: 0000000000000000 x13: 000000000000e380 x12: 0000000000000018
<4>[   29.158248] x11: ffffff80c2a7fd10 x10: 0000000000000000 x9 : 0000000100000000
<4>[   29.158257] x8 : 0000000000000000 x7 : 7f7f7f7f7f7f7f7f x6 : 2d7223ff6364626d
<4>[   29.158266] x5 : 0000008000000000 x4 : 0000000000000020 x3 : 2e7325006465636e
<4>[   29.158275] x2 : ffffffdc11afeff8 x1 : 0000000000000000 x0 : ffffffdc11be4d0c
<4>[   29.158285] Call trace:
<4>[   29.158290]  klist_remove+0x90/0x158
<4>[   29.158298]  device_release_driver_internal+0x20c/0x268
<4>[   29.158308]  device_release_driver+0x1c/0x30
<4>[   29.158316]  usb_driver_release_interface+0x70/0x88
<4>[   29.158325]  btusb_mtk_release_iso_intf+0x68/0xd8 [btusb (HASH:e8b6 5)]
<4>[   29.158347]  btusb_mtk_reset+0x5c/0x480 [btusb (HASH:e8b6 5)]
<4>[   29.158361]  hci_cmd_sync_work+0x10c/0x188 [bluetooth (HASH:a4fa 6)]
<4>[   29.158430]  process_scheduled_works+0x258/0x4e8
<4>[   29.158441]  worker_thread+0x300/0x428
<4>[   29.158448]  kthread+0x108/0x1d0
<4>[   29.158455]  ret_from_fork+0x10/0x20
<0>[   29.158467] Code: 91343000 940139d1 f9400268 927ff914 (f9401297)
<4>[   29.158474] ---[ end trace 0000000000000000 ]---
<0>[   29.167129] Kernel panic - not syncing: Oops: Fatal exception
<2>[   29.167144] SMP: stopping secondary CPUs
<4>[   29.167158] ------------[ cut here ]------------

Fixes: ceac1cb0259d ("Bluetooth: btusb: mediatek: add ISO data transmission functions")

Signed-off-by: Chris Lu <chris.lu@mediatek.com>
---
 drivers/bluetooth/btusb.c | 34 +++++++++++++++++++++++++++-------
 1 file changed, 27 insertions(+), 7 deletions(-)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index e0e30f00a678..fcc62e2fb641 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -2741,9 +2741,16 @@ static int btusb_recv_event_realtek(struct hci_dev *hdev, struct sk_buff *skb)
 
 static void btusb_mtk_claim_iso_intf(struct btusb_data *data)
 {
-	struct btmtk_data *btmtk_data = hci_get_priv(data->hdev);
+	struct btmtk_data *btmtk_data;
 	int err;
 
+	if (!data->hdev)
+		return;
+
+	btmtk_data = hci_get_priv(data->hdev);
+	if (!btmtk_data)
+		return;
+
 	/*
 	 * The function usb_driver_claim_interface() is documented to need
 	 * locks held if it's not called from a probe routine. The code here
@@ -2765,17 +2772,30 @@ static void btusb_mtk_claim_iso_intf(struct btusb_data *data)
 
 static void btusb_mtk_release_iso_intf(struct hci_dev *hdev)
 {
-	struct btmtk_data *btmtk_data = hci_get_priv(hdev);
+	struct btmtk_data *btmtk_data;
+
+	if (!hdev)
+		return;
+
+	btmtk_data = hci_get_priv(hdev);
+	if (!btmtk_data)
+		return;
 
 	if (test_bit(BTMTK_ISOPKT_OVER_INTR, &btmtk_data->flags)) {
 		usb_kill_anchored_urbs(&btmtk_data->isopkt_anchor);
 		clear_bit(BTMTK_ISOPKT_RUNNING, &btmtk_data->flags);
 
-		dev_kfree_skb_irq(btmtk_data->isopkt_skb);
-		btmtk_data->isopkt_skb = NULL;
-		usb_set_intfdata(btmtk_data->isopkt_intf, NULL);
-		usb_driver_release_interface(&btusb_driver,
-					     btmtk_data->isopkt_intf);
+		if (btmtk_data->isopkt_skb) {
+			dev_kfree_skb_irq(btmtk_data->isopkt_skb);
+			btmtk_data->isopkt_skb = NULL;
+		}
+
+		if (btmtk_data->isopkt_intf) {
+			usb_set_intfdata(btmtk_data->isopkt_intf, NULL);
+			usb_driver_release_interface(&btusb_driver,
+						     btmtk_data->isopkt_intf);
+			btmtk_data->isopkt_intf = NULL;
+		}
 	}
 
 	clear_bit(BTMTK_ISOPKT_OVER_INTR, &btmtk_data->flags);
-- 
2.45.2