Comment 4 for bug 1113395

Note that both Krusader KIO and smbclient works correctly. I tried to enable more verbose debug messages via /proc/fs/cifs/cifsFYI:

[ 3714.113990] /build/buildd/linux-3.8.0/fs/cifs/cifsfs.c: Devname: //192.168.1.104/stuff flags: 0
[ 3714.114087] /build/buildd/linux-3.8.0/fs/cifs/connect.c: Username: admin
[ 3714.114102] /build/buildd/linux-3.8.0/fs/cifs/connect.c: file mode: 0x1ed dir mode: 0x1ed
[ 3714.114398] /build/buildd/linux-3.8.0/fs/cifs/connect.c: CIFS VFS: in cifs_mount as Xid: 26 with uid: 0
[ 3714.114410] /build/buildd/linux-3.8.0/fs/cifs/connect.c: UNC: \\192.168.1.104\stuff
[ 3714.114471] /build/buildd/linux-3.8.0/fs/cifs/connect.c: Socket created
[ 3714.114486] /build/buildd/linux-3.8.0/fs/cifs/connect.c: sndbuf 16384 rcvbuf 87380 rcvtimeo 0x6d6
[ 3714.117756] /build/buildd/linux-3.8.0/fs/cifs/fscache.c: cifs_fscache_get_client_cookie: (0xe7a8a800/0xe7879120)
[ 3714.117783] /build/buildd/linux-3.8.0/fs/cifs/connect.c: CIFS VFS: in cifs_get_smb_ses as Xid: 27 with uid: 0
[ 3714.117793] /build/buildd/linux-3.8.0/fs/cifs/connect.c: Existing smb sess not found
[ 3714.117821] /build/buildd/linux-3.8.0/fs/cifs/cifssmb.c: secFlags 0x81
[ 3714.117834] /build/buildd/linux-3.8.0/fs/cifs/cifssmb.c: NTLMSSP only mechanism, enable extended security
[ 3714.117851] /build/buildd/linux-3.8.0/fs/cifs/transport.c: For smb_command 114
[ 3714.117864] /build/buildd/linux-3.8.0/fs/cifs/transport.c: Sending smb: smb_len=78
[ 3714.117986] /build/buildd/linux-3.8.0/fs/cifs/connect.c: Demultiplex PID: 16733
[ 3714.176314] /build/buildd/linux-3.8.0/fs/cifs/connect.c: RFC1002 header 0x61
[ 3714.176373] /build/buildd/linux-3.8.0/fs/cifs/transport.c: cifs_sync_mid_result: cmd=114 mid=1 state=4
[ 3714.176386] /build/buildd/linux-3.8.0/fs/cifs/cifssmb.c: Dialect: 2
[ 3714.176393] /build/buildd/linux-3.8.0/fs/cifs/cifssmb.c: negprot rc 0
[ 3714.176400] /build/buildd/linux-3.8.0/fs/cifs/connect.c: Security Mode: 0x3 Capabilities: 0x80f3fd TimeAdjust: -3600
[ 3714.176405] /build/buildd/linux-3.8.0/fs/cifs/sess.c: sess setup type 3
[ 3714.176414] /build/buildd/linux-3.8.0/fs/cifs/sess.c: ntlmssp session setup phase 1
[ 3714.176424] /build/buildd/linux-3.8.0/fs/cifs/transport.c: For smb_command 115
[ 3714.176429] /build/buildd/linux-3.8.0/fs/cifs/transport.c: Sending smb: smb_len=204
[ 3714.178032] /build/buildd/linux-3.8.0/fs/cifs/connect.c: RFC1002 header 0x23
[ 3714.178073] /build/buildd/linux-3.8.0/fs/cifs/transport.c: cifs_sync_mid_result: cmd=115 mid=2 state=4
[ 3714.178083] /build/buildd/linux-3.8.0/fs/cifs/netmisc.c: Mapping smb error code 0x50001 to POSIX err -13
[ 3714.178089] /build/buildd/linux-3.8.0/fs/cifs/misc.c: Null buffer passed to cifs_small_buf_release
[ 3714.178096] /build/buildd/linux-3.8.0/fs/cifs/sess.c: ssetup freeing small buf c71f3d40
[ 3714.178101] CIFS VFS: Send error in SessSetup = -13
[ 3714.178111] /build/buildd/linux-3.8.0/fs/cifs/connect.c: CIFS VFS: leaving cifs_get_smb_ses (xid = 27) rc = -13
[ 3714.178128] /build/buildd/linux-3.8.0/fs/cifs/fscache.c: cifs_fscache_release_client_cookie: (0xe7a8a800/0xe7879120)
[ 3714.178383] /build/buildd/linux-3.8.0/fs/cifs/connect.c: CIFS VFS: leaving cifs_mount (xid = 26) rc = -13
[ 3714.178393] CIFS VFS: cifs_mount failed w/return code = -13

Note that the samba server is the Synology Diskstation 3.2