linux-kernel - Re: [syzbot] [bluetooth?] [usb?] memory leak in __hci_cmd_sync

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Message-ID: <tencent_879590E9A2ED4ACD1C79366D5C2DE96FF00A@qq.com>
Date: Sun, 23 Nov 2025 22:33:36 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+f098d64cc684b8dbaf65@...kaller.appspotmail.com
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bluetooth?] [usb?] memory leak in __hci_cmd_sync_sk

#syz test

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 6e76798ec786..f3898f8b007e 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -173,6 +173,8 @@ struct sk_buff *__hci_cmd_sync_sk(struct hci_dev *hdev, u16 opcode, u32 plen,
 	if (err < 0)
 		return ERR_PTR(err);
 
+	skb = skb_peek_tail(&req.cmd_q);
+retry:
 	err = wait_event_interruptible_timeout(hdev->req_wait_q,
 					       hdev->req_status != HCI_REQ_PEND,
 					       timeout);
@@ -186,6 +188,11 @@ struct sk_buff *__hci_cmd_sync_sk(struct hci_dev *hdev, u16 opcode, u32 plen,
 		break;
 
 	case HCI_REQ_CANCELED:
+		if (!skb_queue_empty(&hdev->cmd_q) && hdev->req_skb != skb) {
+			atomic_set(&hdev->cmd_cnt, 1);
+			queue_work(hdev->workqueue, &hdev->cmd_work);
+			goto retry;
+		}
 		err = -hdev->req_result;
 		break;
 
diff --git a/drivers/bluetooth/hci_vhci.c b/drivers/bluetooth/hci_vhci.c
index 2fef08254d78..2e12615f539e 100644
--- a/drivers/bluetooth/hci_vhci.c
+++ b/drivers/bluetooth/hci_vhci.c
@@ -75,6 +75,10 @@ static int vhci_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
 {
 	struct vhci_data *data = hci_get_drvdata(hdev);
 
+	printk("skb: %p refcnt: %u,  data inited: %d, %s\n",
+		skb, refcount_read(&skb->users),
+		atomic_read(&data->initialized),
+		__func__);
 	memcpy(skb_push(skb, 1), &hci_skb_pkt_type(skb), 1);
 
 	skb_queue_tail(&data->readq, skb);
@@ -587,6 +591,8 @@ static ssize_t vhci_read(struct file *file,
 		skb = skb_dequeue(&data->readq);
 		if (skb) {
 			ret = vhci_put_user(data, skb, buf, count);
+			printk("skb: %p refcnt: %u len: %u, data: %p, ret: %ld, count: %lu, %s\n",
+				skb, refcount_read(&skb->users), skb->len, skb->data, ret, count, __func__);
 			if (ret < 0)
 				skb_queue_head(&data->readq, skb);
 			else