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

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Date:   Mon, 22 Mar 2021 14:02:15 +0800
From:   Archie Pusaka <apusaka@...gle.com>
To:     linux-bluetooth <linux-bluetooth@...r.kernel.org>,
        Marcel Holtmann <marcel@...tmann.org>
Cc:     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>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH] Bluetooth: Set CONF_NOT_COMPLETE as l2cap_chan default

From: Archie Pusaka <apusaka@...omium.org>

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(+)

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 374cc32d7138..59ab9689b37d 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -516,7 +516,9 @@ void l2cap_chan_set_defaults(struct l2cap_chan *chan)
 	chan->flush_to = L2CAP_DEFAULT_FLUSH_TO;
 	chan->retrans_timeout = L2CAP_DEFAULT_RETRANS_TO;
 	chan->monitor_timeout = L2CAP_DEFAULT_MONITOR_TO;
+
 	chan->conf_state = 0;
+	set_bit(CONF_NOT_COMPLETE, &chan->conf_state);
 
 	set_bit(FLAG_FORCE_ACTIVE, &chan->flags);
 }
-- 
2.31.0.rc2.261.g7f71774620-goog