From: Nick Pelly <npelly@google.com>
Date: Tue, 22 Sep 2009 01:20:03 +0000 (-0700)
Subject: Bluetooth: Do not call rfcomm_session_put() due to RFCOMM UA on closed socket.
X-Git-Tag: firefly_0821_release~11672
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=43a3de3be869aa4417817b94b7dde35267951418;p=firefly-linux-kernel-4.4.55.git

Bluetooth: Do not call rfcomm_session_put() due to RFCOMM UA on closed socket.

Processing a RFCOMM UA frame when the socket is closed and we were not the
RFCOMM initiator would cause rfcomm_session_put() to be called twice during
rfcomm_process_rx(). This would cause a kernel panic in rfcomm_session_close.

This could be easily reproduced during disconnect with devices such as
Motorola H270 that send RFCOMM UA followed quickly by L2CAP disconnect request.
This hcidump for this looks like:

2009-09-21 17:22:37.788895 < ACL data: handle 1 flags 0x02 dlen 8
   L2CAP(d): cid 0x0041 len 4 [psm 3]
     RFCOMM(s): DISC: cr 0 dlci 20 pf 1 ilen 0 fcs 0x7d
2009-09-21 17:22:37.906204 > HCI Event: Number of Completed Packets (0x13)
plen 5
   handle 1 packets 1
2009-09-21 17:22:37.933090 > ACL data: handle 1 flags 0x02 dlen 8
   L2CAP(d): cid 0x0040 len 4 [psm 3]
     RFCOMM(s): UA: cr 0 dlci 20 pf 1 ilen 0 fcs 0x57
2009-09-21 17:22:38.636764 < ACL data: handle 1 flags 0x02 dlen 8
   L2CAP(d): cid 0x0041 len 4 [psm 3]
     RFCOMM(s): DISC: cr 0 dlci 0 pf 1 ilen 0 fcs 0x9c
2009-09-21 17:22:38.744125 > HCI Event: Number of Completed Packets (0x13)
plen 5
   handle 1 packets 1
2009-09-21 17:22:38.763687 > ACL data: handle 1 flags 0x02 dlen 8
   L2CAP(d): cid 0x0040 len 4 [psm 3]
     RFCOMM(s): UA: cr 0 dlci 0 pf 1 ilen 0 fcs 0xb6
2009-09-21 17:22:38.783554 > ACL data: handle 1 flags 0x02 dlen 12
   L2CAP(s): Disconn req: dcid 0x0040 scid 0x0041

Avoid calling rfcomm_session_put() twice by skipping this call
in rfcomm_recv_ua() if the socket is closed.

Signed-off-by: Nick Pelly <npelly@google.com>
---

diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c
index f224b2db0249..d101f7b3505e 100644
--- a/net/bluetooth/rfcomm/core.c
+++ b/net/bluetooth/rfcomm/core.c
@@ -1147,7 +1147,8 @@ static int rfcomm_recv_ua(struct rfcomm_session *s, u8 dlci)
 			break;
 
 		case BT_DISCONN:
-			rfcomm_session_put(s);
+			if (s->sock->sk->sk_state != BT_CLOSED)
+				rfcomm_session_put(s);
 			break;
 		}
 	}