Re: [PATCH v2] Bluetooth: check for zapped sk before connecting

[Marcel Holtmann]

Hi Archie,

> There is a possibility of receiving a zapped sock on
> l2cap_sock_connect(). This could lead to interesting crashes, one
> such case is tearing down an already tore l2cap_sock as is happened
> with this call trace:
> 
> __dump_stack lib/dump_stack.c:15 [inline]
> dump_stack+0xc4/0x118 lib/dump_stack.c:56
> register_lock_class kernel/locking/lockdep.c:792 [inline]
> register_lock_class+0x239/0x6f6 kernel/locking/lockdep.c:742
> __lock_acquire+0x209/0x1e27 kernel/locking/lockdep.c:3105
> lock_acquire+0x29c/0x2fb kernel/locking/lockdep.c:3599
> __raw_spin_lock_bh include/linux/spinlock_api_smp.h:137 [inline]
> _raw_spin_lock_bh+0x38/0x47 kernel/locking/spinlock.c:175
> spin_lock_bh include/linux/spinlock.h:307 [inline]
> lock_sock_nested+0x44/0xfa net/core/sock.c:2518
> l2cap_sock_teardown_cb+0x88/0x2fb net/bluetooth/l2cap_sock.c:1345
> l2cap_chan_del+0xa3/0x383 net/bluetooth/l2cap_core.c:598
> l2cap_chan_close+0x537/0x5dd net/bluetooth/l2cap_core.c:756
> l2cap_chan_timeout+0x104/0x17e net/bluetooth/l2cap_core.c:429
> process_one_work+0x7e3/0xcb0 kernel/workqueue.c:2064
> worker_thread+0x5a5/0x773 kernel/workqueue.c:2196
> kthread+0x291/0x2a6 kernel/kthread.c:211
> ret_from_fork+0x4e/0x80 arch/x86/entry/entry_64.S:604
> 
> Signed-off-by: Archie Pusaka <apusaka@xxxxxxxxxxxx>
> Reported-by: syzbot+abfc0f5e668d4099af73@xxxxxxxxxxxxxxxxxxxxxxxxx
> Reviewed-by: Alain Michaud <alainm@xxxxxxxxxxxx>
> Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx>
> Reviewed-by: Guenter Roeck <groeck@xxxxxxxxxxxx>
> ---
> 
> Changes in v2:
> * Modify locking order for better visibility
> 
> net/bluetooth/l2cap_sock.c | 8 ++++++++
> 1 file changed, 8 insertions(+)

patch has been applied to bluetooth-next tree.

Regards

Marcel