linux-kernel - Re: [PATCH] Bluetooth: Set CONF_NOT_COMPLETE as l2cap

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Date:   Mon, 22 Mar 2021 16:59:02 +0100
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Archie Pusaka <apusaka@...gle.com>
Cc:     linux-bluetooth <linux-bluetooth@...r.kernel.org>,
        CrosBT Upstreaming <chromeos-bluetooth-upstreaming@...omium.org>,
        Archie Pusaka <apusaka@...omium.org>,
        syzbot+338f014a98367a08a114@...kaller.appspotmail.com,
        Alain Michaud <alainm@...omium.org>,
        Abhishek Pandit-Subedi <abhishekpandit@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        LKML <linux-kernel@...r.kernel.org>, netdev@...r.kernel.org
Subject: Re: [PATCH] Bluetooth: Set CONF_NOT_COMPLETE as l2cap_chan default

Hi Archie,

> Currently l2cap_chan_set_defaults() reset chan->conf_state to zero.
> However, there is a flag CONF_NOT_COMPLETE which is set when
> creating the l2cap_chan. It is suggested that the flag should be
> cleared when l2cap_chan is ready, but when l2cap_chan_set_defaults()
> is called, l2cap_chan is not yet ready. Therefore, we must set this
> flag as the default.
> 
> Example crash call trace:
> __dump_stack lib/dump_stack.c:15 [inline]
> dump_stack+0xc4/0x118 lib/dump_stack.c:56
> panic+0x1c6/0x38b kernel/panic.c:117
> __warn+0x170/0x1b9 kernel/panic.c:471
> warn_slowpath_fmt+0xc7/0xf8 kernel/panic.c:494
> debug_print_object+0x175/0x193 lib/debugobjects.c:260
> debug_object_assert_init+0x171/0x1bf lib/debugobjects.c:614
> debug_timer_assert_init kernel/time/timer.c:629 [inline]
> debug_assert_init kernel/time/timer.c:677 [inline]
> del_timer+0x7c/0x179 kernel/time/timer.c:1034
> try_to_grab_pending+0x81/0x2e5 kernel/workqueue.c:1230
> cancel_delayed_work+0x7c/0x1c4 kernel/workqueue.c:2929
> l2cap_clear_timer+0x1e/0x41 include/net/bluetooth/l2cap.h:834
> l2cap_chan_del+0x2d8/0x37e net/bluetooth/l2cap_core.c:640
> l2cap_chan_close+0x532/0x5d8 net/bluetooth/l2cap_core.c:756
> l2cap_sock_shutdown+0x806/0x969 net/bluetooth/l2cap_sock.c:1174
> l2cap_sock_release+0x64/0x14d net/bluetooth/l2cap_sock.c:1217
> __sock_release+0xda/0x217 net/socket.c:580
> sock_close+0x1b/0x1f net/socket.c:1039
> __fput+0x322/0x55c fs/file_table.c:208
> ____fput+0x17/0x19 fs/file_table.c:244
> task_work_run+0x19b/0x1d3 kernel/task_work.c:115
> exit_task_work include/linux/task_work.h:21 [inline]
> do_exit+0xe4c/0x204a kernel/exit.c:766
> do_group_exit+0x291/0x291 kernel/exit.c:891
> get_signal+0x749/0x1093 kernel/signal.c:2396
> do_signal+0xa5/0xcdb arch/x86/kernel/signal.c:737
> exit_to_usermode_loop arch/x86/entry/common.c:243 [inline]
> prepare_exit_to_usermode+0xed/0x235 arch/x86/entry/common.c:277
> syscall_return_slowpath+0x3a7/0x3b3 arch/x86/entry/common.c:348
> int_ret_from_sys_call+0x25/0xa3
> 
> Signed-off-by: Archie Pusaka <apusaka@...omium.org>
> Reported-by: syzbot+338f014a98367a08a114@...kaller.appspotmail.com
> Reviewed-by: Alain Michaud <alainm@...omium.org>
> Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
> Reviewed-by: Guenter Roeck <groeck@...omium.org>
> ---
> 
> net/bluetooth/l2cap_core.c | 2 ++
> 1 file changed, 2 insertions(+)

patch has been applied to bluetooth-next tree.

Regards

Marcel