From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi2-f4.google.com (mail-oi2-f4.google.com [74.125.231.196]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3236D2E6CB8 for ; Sat, 29 Aug 2026 15:29:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.231.196 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788017374; cv=none; b=rm4cAeOckmxTFhaK2csaLx7Q6vbZ3EeIWIENFFRMQ7ZmP54ptDvP7e0x4VpMtjLCP83coH5DI2iNb5HuKbSahLgP4YQZuKLMU0enHxj+z7H0ib8/adx+/enZ1ueS3YolTDy0vDJIZEp6b5uO1eca+B692uV7SlsCPms7nZXbilw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788017374; c=relaxed/simple; bh=CMjiRMXOFhOQJ3t7mMhYPWlT9GWHNsHC2vJnmo61tCk=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=tSNa/Jgu8b96kCCkwaMRI19ZhM2BCoWnPaw6wG69/1Mc97SfW/r2yMB8+N+6Sh11Cu0c87lT3llYY7zjDK+NMqlAyncDPOCNqOXXmrlojrG+andIiB+a2ua/D/09aXrZVizyJbZ5rQQXnTHl+4X8bzdSdwDpvjzqaL3lMlkJ1Rw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=74.125.231.196 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oi2-f4.google.com with SMTP id 5614622812f47-4ab2d8e7e4cso470988b6e.1 for ; Sat, 29 Aug 2026 08:29:33 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788017372; x=1788622172; h=content-type:to:from:subject:message-id:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=qzsG6loT0ZKDWeUwY7zsbCAw31VaYMQZw7KvYQB7hbk=; b=HOAwDgckwVZTZKzZzQn4WToIGoosaPAzpP8rQw23lmHkDHpMk4gLEY9dwLNGogrmbO 1doD86wykInAz7Abj2YhMEKDCYpM4hfqSL/AXB9s02DUGzpr/nbG6K8zuYbxTX0M3KBf hC0IR2aghwLbE0kaG62G0VmBuf4S7FrqOnG+7tCSbfP7YoKZbFfC8e03Qj6Yoo9KcfHT m7QS5IqUDiiSmVP1EyMoTlb5i7aDe96nlZ+wtMSKHRtcYdHotzDxcEs77HpEflw2MExH qEs9FTWDsAIlNL0Di4iQTSoFiE/MdA6uaOy7iaqP+nbPpdG+1uhEXWWgXWR/YLRzE+5F gsCw== X-Forwarded-Encrypted: i=1; AHgh+RqkSWdi+/NINBkSFP41BCF8lT+4PviuywCi0f0RgXyogQwGQqqwfBfVqtW3F++IRPU6CF9QF9dOELlTo/A=@vger.kernel.org X-Gm-Message-State: AFuF++mNexOosIHg9PKQFGC4WWA9oSMyb4gz2/L9A3Mh9lFjfq3Okwu+ ZV/HxN1Epwf9vT98kdDbvk9moSzpfNBy24HS9/jg5lVRaKfGIgw00B7IsbiU4SyWUEKukwuxvmg dtF3YnByk9XgwMbpVeM0YWMiDP0djmgd9Kyh5Y2p4xFQjjuE7z/dCuX1dicg= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:2388:b0:4b3:1e40:640b with SMTP id 5614622812f47-4b39800d0ecmr15540866b6e.6.1788017372140; Sat, 29 Aug 2026 08:29:32 -0700 (PDT) Date: Sat, 29 Aug 2026 08:29:32 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a92fadc.08e933ee.dbf97.008f.GAE@google.com> Subject: [syzbot] [bluetooth?] possible deadlock in rfcomm_security_cfm From: syzbot To: linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, luiz.dentz@gmail.com, marcel@holtmann.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: cf72cbb39da8 Merge tag 'io_uring-7.3-20260828' of git://gi.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=11b8ae25580000 kernel config: https://syzkaller.appspot.com/x/.config?x=8c5c3949d762a91f dashboard link: https://syzkaller.appspot.com/bug?extid=74071deb72339c215b2e compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/7684a30c51dd/disk-cf72cbb3.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/4f401bdb1bb3/vmlinux-cf72cbb3.xz kernel image: https://storage.googleapis.com/syzbot-assets/4379cea44543/bzImage-cf72cbb3.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+74071deb72339c215b2e@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ kworker/u9:2/5598 is trying to acquire lock: ffffffff90f7e040 (rfcomm_mutex){+.+.}-{4:4}, at: rfcomm_security_cfm+0x3f/0x4b0 net/bluetooth/rfcomm/core.c:2222 but task is already holding lock: ffffffff90f51500 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_encrypt_cfm+0x11b/0x740 include/net/bluetooth/hci_core.h:2239 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (hci_cb_list_lock){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5908 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bc0 kernel/locking/mutex.c:821 hci_connect_cfm include/net/bluetooth/hci_core.h:2163 [inline] hci_remote_features_evt+0x485/0x9b0 net/bluetooth/hci_event.c:3786 hci_event_func net/bluetooth/hci_event.c:7887 [inline] hci_event_packet+0x8e9/0xcd0 net/bluetooth/hci_event.c:7938 hci_rx_work+0x451/0xfc0 net/bluetooth/hci_core.c:4041 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387 process_scheduled_works kernel/workqueue.c:3470 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #1 (&hdev->lock){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5908 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bc0 kernel/locking/mutex.c:821 l2cap_chan_connect+0xac/0x2050 net/bluetooth/l2cap_core.c:7266 l2cap_sock_connect+0x37a/0x770 net/bluetooth/l2cap_sock.c:255 kernel_connect+0x107/0x160 net/socket.c:3755 rfcomm_session_create net/bluetooth/rfcomm/core.c:808 [inline] __rfcomm_dlc_open net/bluetooth/rfcomm/core.c:385 [inline] rfcomm_dlc_open+0x838/0xac0 net/bluetooth/rfcomm/core.c:428 rfcomm_sock_connect+0x42c/0x690 net/bluetooth/rfcomm/sock.c:421 connect_socket net/socket.c:2141 [inline] connect_socket net/socket.c:2131 [inline] __sys_connect_file+0x146/0x1a0 net/socket.c:2166 __sys_connect+0x141/0x170 net/socket.c:2183 __do_sys_connect net/socket.c:2189 [inline] __se_sys_connect net/socket.c:2186 [inline] __x64_sys_connect+0x72/0xb0 net/socket.c:2186 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (rfcomm_mutex){+.+.}-{4:4}: check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3181 check_prevs_add kernel/locking/lockdep.c:3300 [inline] validate_chain kernel/locking/lockdep.c:3924 [inline] __lock_acquire+0x1492/0x1ec0 kernel/locking/lockdep.c:5254 lock_acquire kernel/locking/lockdep.c:5908 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bc0 kernel/locking/mutex.c:821 rfcomm_security_cfm+0x3f/0x4b0 net/bluetooth/rfcomm/core.c:2222 hci_encrypt_cfm+0x18e/0x740 include/net/bluetooth/hci_core.h:2242 hci_encrypt_change_evt+0x3e1/0xfb0 net/bluetooth/hci_event.c:3715 hci_event_func net/bluetooth/hci_event.c:7887 [inline] hci_event_packet+0x8e9/0xcd0 net/bluetooth/hci_event.c:7938 hci_rx_work+0x451/0xfc0 net/bluetooth/hci_core.c:4041 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387 process_scheduled_works kernel/workqueue.c:3470 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 other info that might help us debug this: Chain exists of: rfcomm_mutex --> &hdev->lock --> hci_cb_list_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(hci_cb_list_lock); lock(&hdev->lock); lock(hci_cb_list_lock); lock(rfcomm_mutex); *** DEADLOCK *** locks held by kworker/u9:2/5598: 4, last CPU#0: #0: ffff88802e39e940 ((wq_completion)hci3#2){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3362 #1: ffffc9000250fd08 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3363 #2: ffff88807d7b80b8 (&hdev->lock){+.+.}-{4:4}, at: hci_encrypt_change_evt+0x83/0xfb0 net/bluetooth/hci_event.c:3627 #3: ffffffff90f51500 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_encrypt_cfm+0x11b/0x740 include/net/bluetooth/hci_core.h:2239 stack backtrace: CPU: 0 UID: 0 PID: 5598 Comm: kworker/u9:2 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 Workqueue: hci3 hci_rx_work Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1be kernel/locking/lockdep.c:2059 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2191 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3181 check_prevs_add kernel/locking/lockdep.c:3300 [inline] validate_chain kernel/locking/lockdep.c:3924 [inline] __lock_acquire+0x1492/0x1ec0 kernel/locking/lockdep.c:5254 lock_acquire kernel/locking/lockdep.c:5908 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bc0 kernel/locking/mutex.c:821 rfcomm_security_cfm+0x3f/0x4b0 net/bluetooth/rfcomm/core.c:2222 hci_encrypt_cfm+0x18e/0x740 include/net/bluetooth/hci_core.h:2242 hci_encrypt_change_evt+0x3e1/0xfb0 net/bluetooth/hci_event.c:3715 hci_event_func net/bluetooth/hci_event.c:7887 [inline] hci_event_packet+0x8e9/0xcd0 net/bluetooth/hci_event.c:7938 hci_rx_work+0x451/0xfc0 net/bluetooth/hci_core.c:4041 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387 process_scheduled_works kernel/workqueue.c:3470 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 --- This report is generated by a bot. 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