From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from r3-11.sinamail.sina.com.cn (r3-11.sinamail.sina.com.cn [202.108.3.11]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4EDAE302753 for ; Sun, 30 Aug 2026 22:58:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=202.108.3.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788130720; cv=none; b=I8mFWCuD32kMQ2GaN+XiwHmqaWX88N7/8yh5AQiO5Sxplel9QAcksmCPxIhRb1q7vdNv3ztExt/XAJ3wYLXRWcbjbwotyMktuI/78jHNpE3K7iGpCbzgdpvfvuwfRHo/VIYh6xU6n9+1qlu+ETIbjJUtAVtxkXkTxBxLEsnz+04= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788130720; c=relaxed/simple; bh=/G3fUORFPDuiGMJ1TA1RNFwl8lVqunjxfrCc82QFs/o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=oqNEewiQCp9VUWcXq3aUDSndEOTj2y+5PvznYzWs0oKoGBnAh/eUxC9tFn3QeXwERkF3gffbKXKVn/0a7DIFwHFn8nY6JFQiUIzvcx9e/2XG+hyGdC2NJr5R9VssPBpOfMXnfmum5unVLrKunfPZvTXHAdL55e0msLXs3Didslc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com; spf=pass smtp.mailfrom=sina.com; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b=BgFFcdfP; arc=none smtp.client-ip=202.108.3.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sina.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b="BgFFcdfP" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1788130715; bh=Z0H8WgXMhNVB4fhDgpKQZagQDO0oVSF5KidTwQp0HSs=; h=From:Subject:Date:Message-ID; b=BgFFcdfPymJzB0C9BGuH8hLgikf6SVh1TT5TBj9GAIw1z2aHd7kM1nMNd6gTyxoRb +1qiu4FEMEw7K6LoHZmg1+xsvZ84EAVyH+eLj47IY0r3YP9DlThMLVxoaNl+tHMcYO 54RBL4O6rjL3F6BPRHJMEfK3dRHSmzWdo2DJZFeA= X-SMAIL-HELO: localhost.localdomain Received: from unknown (HELO localhost.localdomain)([114.249.62.194]) by sina.com (10.54.253.34) with ESMTP id 6A94B58E00002C32; Sun, 31 Aug 2026 06:58:25 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com Authentication-Results: sina.com; spf=none smtp.mailfrom=hdanton@sina.com; dkim=none header.i=none; dmarc=none action=none header.from=hdanton@sina.com X-SMAIL-MID: 8650696291648 X-SMAIL-UIID: 033BBF74D3B84ACABE7EDB35C4334983-20260831-065825-1 From: Hillf Danton To: syzbot Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [bluetooth?] kernel panic: kernel: panic_on_warn set ... (3) Date: Mon, 31 Aug 2026 06:58:08 +0800 Message-ID: <20260830225812.1943-1-hdanton@sina.com> In-Reply-To: <6a946a97.1d9ded08.62e62.0120.GAE@google.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > Date: Sun, 30 Aug 2026 10:38:31 -0700 [thread overview] > syzbot has found a reproducer for the following issue on: > > HEAD commit: 08dbfad3f504 Merge tag 'for-linus' of git://git.kernel.org.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=14f47379580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e > dashboard link: https://syzkaller.appspot.com/bug?extid=fe5ea83cdd7fc263f452 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10c2a379580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16181e25580000 #syz test --- x/include/net/bluetooth/hci_core.h +++ y/include/net/bluetooth/hci_core.h @@ -1701,9 +1701,13 @@ static inline struct hci_conn *hci_conn_ static inline void hci_conn_drop(struct hci_conn *conn) { + int cnt; + BT_DBG("hcon %p orig refcnt %d", conn, atomic_read(&conn->refcnt)); - if (atomic_dec_and_test(&conn->refcnt)) { + cnt = atomic_dec_return(&conn->refcnt); + WARN_ON(cnt < 0); + if (cnt == 0) { unsigned long timeo; switch (conn->type) { --