commit 820962dc700598ffe8cd21b967e30e7520c34748 upstream.

cifs_call_async() queues the MID to the pending list and calls
smb_send_rqst().  If smb_send_rqst() performs a partial send, it sets
the tcpStatus to CifsNeedReconnect and returns an error code to
cifs_call_async().  In this case, cifs_call_async() removes the MID
from the list and returns to the caller.

However, cifs_call_async() releases the server mutex _before_ removing
the MID.  This means that a cifs_reconnect() can race with this function
and manage to remove the MID from the list and delete the entry before
cifs_call_async() calls cifs_delete_mid().  This leads to various
crashes due to the use after free in cifs_delete_mid().

Task1				Task2

cifs_call_async():
 - rc = -EAGAIN
 - mutex_unlock(srv_mutex)

				cifs_reconnect():
				 - mutex_lock(srv_mutex)
				 - mutex_unlock(srv_mutex)
				 - list_delete(mid)
				 - mid->callback()
				 	cifs_writev_callback():
				 		- mutex_lock(srv_mutex)
						- delete(mid)
				 		- mutex_unlock(srv_mutex)

 - cifs_delete_mid(mid) <---- use after free

Fix this by removing the MID in cifs_call_async() before releasing the
srv_mutex.  Also hold the srv_mutex in cifs_reconnect() until the MIDs
are moved out of the pending list.

Signed-off-by: Rabin Vincent <rabin.vincent@axis.com>
Acked-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Steve French <sfrench@localhost.localdomain>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull SMB3 updates from Steve French:
 "A collection of SMB3 patches adding some reliability features
  (persistent and resilient handles) and improving SMB3 copy offload.

  I will have some additional patches for SMB3 encryption and SMB3.1.1
  signing (important security features), and also for improving SMB3
  persistent handle reconnection (setting ChannelSequence number e.g.)
  that I am still working on but wanted to get this set in since they
  can stand alone"

* 'for-next' of git://git.samba.org/sfrench/cifs-2.6:
  Allow copy offload (CopyChunk) across shares
  Add resilienthandles mount parm
  [SMB3] Send durable handle v2 contexts when use of persistent handles required
  [SMB3] Display persistenthandles in /proc/mounts for SMB3 shares if enabled
  [SMB3] Enable checking for continuous availability and persistent handle support
  [SMB3] Add parsing for new mount option controlling persistent handles
  Allow duplicate extents in SMB3 not just SMB3.1.1

Since many servers (Windows clients, and non-clustered servers) do not
support persistent handles but do support resilient handles, allow
the user to specify a mount option "resilienthandles" in order
to get more reliable connections and less chance of data loss
(at least when SMB2.1 or later).  Default resilient handle
timeout (120 seconds to recent Windows server) is used.

Reviewed-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <steve.french@primarydata.com>

Validate "persistenthandles" and "nopersistenthandles" mount options against
the support the server claims in negotiate and tree connect SMB3 responses.

Signed-off-by: Steve French <steve.french@primarydata.com>
Reviewed-by: Pavel Shilovsky <pshilovsky@samba.org>

"nopersistenthandles" and "persistenthandles" mount options added.
The former will not request persistent handles on open even when
SMB3 negotiated and Continuous Availability share.  The latter
will request persistent handles (as long as server notes the
capability in protocol negotiation) even if share is not Continuous
Availability share.

Signed-off-by: Steve French <steve.french@primarydata.com>
Reviewed-by: Pavel Shilovsky <pshilovsky@samba.org>

Merge the type-specific data with the payload data into one four-word chunk
as it seems pointless to keep them separate.

Use user_key_payload() for accessing the payloads of overloaded
user-defined keys.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-cifs@vger.kernel.org
cc: ecryptfs@vger.kernel.org
cc: linux-ext4@vger.kernel.org
cc: linux-f2fs-devel@lists.sourceforge.net
cc: linux-nfs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: linux-ima-devel@lists.sourceforge.net

In a dfs setup where the client transitions from a server which supports
posix paths to a server which doesn't support posix paths, the flag
CIFS_MOUNT_POSIX_PATHS is not reset. This leads to the wrong directory
separator being used causing smb commands to fail.

Consider the following case where a dfs share on a samba server points
to a share on windows smb server.
 # mount -t cifs -o .. //vm140-31/dfsroot/testwin/
 # ls -l /mnt; touch /mnt/a
 total 0
 touch: cannot touch ‘/mnt/a’: No such file or directory

Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Acked-by: Jeff Layton <jlayton@samba.org>
Signed-off-by: Steve French <steve.french@primarydata.com>

Most people think of SMB 3.1.1 as SMB version 3.11 so add synonym
for "vers=3.1.1" of "vers=3.11" on mount.

Also make sure that unlike SMB3.0 and 3.02 we don't send
validate negotiate on mount (it is handled by negotiate contexts) -
add list of SMB3.11 specific functions (distinct from 3.0 dialect).

Signed-off-by: Steve French <steve.french@primarydata.com>w

Parses and recognizes "vers=3.1.1" on cifs mount and allows sending
0x0311 as a new CIFS/SMB3 dialect. Subsequent patches will add
the new negotiate contexts and updated session setup

Reviewed-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: Steve French <steve.french@primarydata.com>

This patch fixes a race condition that occurs when connecting
to a NT 3.51 host without specifying a NetBIOS name.
In that case a RFC1002_NEGATIVE_SESSION_RESPONSE is received
and the SMB negotiation is reattempted, but under some conditions
it leads SendReceive() to hang forever while waiting for srv_mutex.
This, in turn, sets the calling process to an uninterruptible sleep
state and makes it unkillable.

The solution is to unlock the srv_mutex acquired in the demux
thread *before* going to sleep (after the reconnect error) and
before reattempting the connection.