[Samba] cifs.ko v2.1 bug (kernel 4.15)

[Chad William Seys]

Hi all,
   I have observed in kernel 4.15 cifs.ko using protocol v2.1 getting 
confused about whether a "filesystem object" is a file or a directory.
   The true state in the example below is that "Alien" is directory and 
"alien" is a (perl) file.
   However, 'file' reports the type to be the same and matching the 
first object accessed, e.g.

Both are perl scripts (dmesg and pcap log linked):
root at tardis01:/# mount /smbbackupdir/smb01
root at tardis01:/# file /smbbackupdir/smb01/home/eleonard/utils/alien/alien
/smbbackupdir/smb01/home/eleonard/utils/alien/alien: Perl script text 
executable
root at tardis01:/# file /smbbackupdir/smb01/home/eleonard/utils/alien/Alien
/smbbackupdir/smb01/home/eleonard/utils/alien/Alien: Perl script text 
executable

Both are directories:
root at tardis01:/# mount /smbbackupdir/smb01
root at tardis01:/# file /smbbackupdir/smb01/home/eleonard/utils/alien/Alien
/smbbackupdir/smb01/home/eleonard/utils/alien/Alien: directory
root at tardis01:/# file /smbbackupdir/smb01/home/eleonard/utils/alien/alien
/smbbackupdir/smb01/home/eleonard/utils/alien/alien: directory

Strangely, copying to a different directory makes this non-reproducible:
root at tardis01:/# mount /smbbackupdir/smb01
root at tardis01:/# file /smbbackupdir/smb01/home/cwseys/utils/alien/Alien/
/smbbackupdir/smb01/home/cwseys/utils/alien/Alien/: directory
root at tardis01:/# file /smbbackupdir/smb01/home/cwseys/utils/alien/alien
/smbbackupdir/smb01/home/cwseys/utils/alien/alien: writable, executable, 
regular file, no read permission

Using protocol v1.0 makes problem go away (dmesg and pcap log linked)
root at tardis01:/# mount /smbbackupdir/smb01
root at tardis01:/# file /smbbackupdir/smb01/home/eleonard/utils/alien/Alien/
/smbbackupdir/smb01/home/eleonard/utils/alien/Alien/: directory
root at tardis01:/# file /smbbackupdir/smb01/home/eleonard/utils/alien/alien
/smbbackupdir/smb01/home/eleonard/utils/alien/alien: Perl script text 
executable

The fstab line (vers=1.0, switch to vers=2.1 as needed):
//smb01.physics.wisc.edu/smb    /smbbackupdir/smb01     cifs 
vers=1.0,sec=krb5,multiuser,username=backupadmin at PHYSICS.WISC.EDU      0 
       0

I've linked 4 files to this email:
* trace_v1.log (763 bytes) hosted on Box: 
https://uwmadison.box.com/s/u1acmjy7479id3oyqwkckanyjwbuvnlz
* trace_v1.pcap (1.2 MB) hosted on Box: 
https://uwmadison.box.com/s/f0z1daqz9acsen24fgkwmrrih9cd242u
* trace_v2.1.pcap (76.9 MB) hosted on Box: 
https://uwmadison.box.com/s/ppw29iviqn26vbvspfta9ol1whqsvz5j
* trace_v2.1.log (763 bytes) hosted on Box: 
https://uwmadison.box.com/s/1ctdf3ep9nsgv3n3gsmsdtnttv1sir6o

This is on Debian Stretch with backported kernel version 4.15+91~bpo9+1 .
Let me know if I can provide any more info,
Chad.