linux-kernel - Re: [syzbot] [bluetooth?] possible deadlock in touch_wq_lockdep

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Message-Id: <20240703102633.2821-1-hdanton@sina.com>
Date: Wed,  3 Jul 2024 18:26:33 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+91dbdfecdd3287734d8e@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bluetooth?] possible deadlock in touch_wq_lockdep_map

On Tue, 02 Jul 2024 18:47:23 -0700
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    734610514cb0 Merge tag 'erofs-for-6.10-rc7-fixes' of git:/..
> git tree:       upstream
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1424d281980000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git  734610514cb0

--- x/net/bluetooth/hci_core.c
+++ y/net/bluetooth/hci_core.c
@@ -1075,6 +1075,7 @@ static void hci_power_off(struct work_st
 static void hci_error_reset(struct work_struct *work)
 {
 	struct hci_dev *hdev = container_of(work, struct hci_dev, error_reset);
+	bool put;
 
 	hci_dev_hold(hdev);
 	BT_DBG("%s", hdev->name);
@@ -1084,10 +1085,13 @@ static void hci_error_reset(struct work_
 	else
 		bt_dev_err(hdev, "hardware error 0x%2.2x", hdev->hw_error_code);
 
+	put = !test_bit(HCI_UP, &hdev->flags);
+
 	if (!hci_dev_do_close(hdev))
 		hci_dev_do_open(hdev);
 
-	hci_dev_put(hdev);
+	if (put)
+		hci_dev_put(hdev);
 }
 
 void hci_uuids_clear(struct hci_dev *hdev)
--