[PATCH BlueZ v1 2/4] monitor: Fix crash parsing notification

[Luiz Augusto von Dentz <luiz.dentz@gmail.com>]

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

This fixes the following crash caused by notify callback being NULL:

Jump to the invalid address stated on the next line
   at 0x0: ???
   by 0x1E8375: print_notify (att.c:5420)
   by 0x1E9464: att_multiple_vl_rsp (att.c:5463)
   by 0x20D39E: att_packet (att.c:5637)
   by 0x1B2054: l2cap_frame (l2cap.c:2567)
   by 0x1B4A4D: l2cap_packet (l2cap.c:2708)
   by 0x19AD43: packet_hci_acldata (packet.c:12522)
   by 0x19CF07: packet_monitor (packet.c:4249)
   by 0x152405: data_callback (control.c:973)
   by 0x2204F6: mainloop_run (mainloop.c:106)
   by 0x221017: mainloop_run_with_signal (mainloop-notify.c:189)
   by 0x14F387: main (main.c:298)
 Address 0x0 is not stack'd, malloc'd or (recently) free'd
---
 monitor/att.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/monitor/att.c b/monitor/att.c
index a23347ef7..73a616584 100644
--- a/monitor/att.c
+++ b/monitor/att.c
@@ -4646,7 +4646,8 @@ static void print_notify(const struct l2cap_frame *frame, uint16_t handle,
 		frame = &clone;
 	}
 
-	handler->notify(frame);
+	if (handler->notify)
+		handler->notify(frame);
 }
 
 static void att_handle_value_notify(const struct l2cap_frame *frame)
-- 
2.45.0