cifs: eliminate some more premature cifsd exits

If the tcpStatus is still CifsNew, the main cifs_demultiplex_loop can
break out prematurely in some cases. This is wrong as we will almost
always have other structures with pointers to the TCP_Server_Info. If
the main loop breaks under any other condition other than tcpStatus ==
CifsExiting, then it'll face a use-after-free situation.

I don't see any reason to treat a CifsNew tcpStatus differently than
CifsGood. I believe we'll still want to attempt to reconnect in either
case. What should happen in those situations is that the MIDs get marked
as MID_RETRY_NEEDED. This will make CIFSSMBNegotiate return -EAGAIN, and
then the caller can retry the whole thing on a newly reconnected socket.
If that fails again in the same way, the caller of cifs_get_smb_ses
should tear down the TCP_Server_Info struct.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 12 insertions, 29 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 5f68b968faa7..5fde83f0c75e 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -416,14 +416,6 @@ incomplete_rcv:
                         } else
                                 continue;
                 } else if (length <= 0) {
-                        if (server->tcpStatus == CifsNew) {
-                                cFYI(1, "tcp session abend after SMBnegprot");
-                                /* some servers kill the TCP session rather than
-                                   returning an SMB negprot error, in which
-                                   case reconnecting here is not going to help,
-                                   and so simply return error to mount */
-                                break;
-                        }
                         cFYI(1, "Reconnect after unexpected peek error %d",
                                 length);
                         cifs_reconnect(server);
@@ -464,27 +456,18 @@ incomplete_rcv:
                            an error on SMB negprot response */
                         cFYI(1, "Negative RFC1002 Session Response Error 0x%x)",
                                 pdu_length);
-                        if (server->tcpStatus == CifsNew) {
-                                /* if nack on negprot (rather than
-                                ret of smb negprot error) reconnecting
-                                not going to help, ret error to mount */
-                                break;
-                        } else {
-                                /* give server a second to
-                                clean up before reconnect attempt */
-                                msleep(1000);
-                                /* always try 445 first on reconnect
-                                since we get NACK on some if we ever
-                                connected to port 139 (the NACK is
-                                since we do not begin with RFC1001
-                                session initialize frame) */
-                                server->addr.sockAddr.sin_port =
-                                        htons(CIFS_PORT);
-                                cifs_reconnect(server);
-                                csocket = server->ssocket;
-                                wake_up(&server->response_q);
-                                continue;
-                        }
+                        /* give server a second to clean up  */
+                        msleep(1000);
+                        /* always try 445 first on reconnect since we get NACK
+                         * on some if we ever connected to port 139 (the NACK
+                         * is since we do not begin with RFC1001 session
+                         * initialize frame)
+                         */
+                        server->addr.sockAddr.sin_port = htons(CIFS_PORT);
+                        cifs_reconnect(server);
+                        csocket = server->ssocket;
+                        wake_up(&server->response_q);
+                        continue;
                 } else if (temp != (char) 0) {
                         cERROR(1, "Unknown RFC 1002 frame");
                         cifs_dump_mem(" Received Data: ", (char *)smb_buffer,