[Pkg-samba-maint] Bug#803941: samba: cp and cat return an endless stream of 0s when reading a file on a samba share

[Matija Nalis]

Package: samba
Version: 2:4.2.10+dfsg-0+deb8u2
Followup-For: Bug #803941

It seems that the bug happens when using too big read buffer.

I can work around it on client side by either:

1) mounting with "-o rsize=16384"
   (or actually any number lower than 131071, which is 2^17-1; just playing it safe here)

   by default mount.cifs from Debian Jessie with kernel linux-image-3.16.0-4-amd64 3.16.7-ckt25-2
   will do mount with CIFS 1.0 and too big rsize:

   //merlin.tomsoft.lan/ganeti2-blade /var/lib/ganeti/export cifs rw,relatime,vers=1.0,cache=strict,domain=MERLIN,uid=0,noforceuid,gid=0,noforcegid,addr=10.66.2.10,unix,posixpaths,serverino,acl,rsize=1048576,wsize=65536,actimeo=1 0 0

2) mounting with (at least) "-o vers=3.0" (or anything at or above 2.0; which seems to force rsize=65536)
   
   (Unfortunately, trying to force it on the server side with "client min protocol = SMB2" does not seem to work
   maybe some of the cache/aio options would, but it is production samba server here which I can't disturb too much...)

-- System Information:
Debian Release: 8.4
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.16.0-4-amd64 (SMP w/2 CPU cores)
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)
Shell: /bin/sh linked to /bin/dash
Init: sysvinit (via /sbin/init)

Versions of packages samba depends on:
ii  adduser                              3.113+nmu3
ii  dpkg                                 1.17.26
ii  libbsd0                              0.7.0-2
ii  libc6                                2.19-18+deb8u4
ii  libhdb9-heimdal [heimdal-hdb-api-8]  1.6~rc2+dfsg-9
ii  libldb1                              2:1.1.20-0+deb8u1
ii  libpam-modules                       1.1.8-3.1+deb8u1+b1
ii  libpam-runtime                       1.1.8-3.1+deb8u1
ii  libpopt0                             1.16-10
ii  libpython2.7                         2.7.9-2
ii  libtalloc2                           2.1.2-0+deb8u1
ii  libtdb1                              1.3.6-0+deb8u1
ii  libtevent0                           0.9.25-0+deb8u1
ii  lsb-base                             4.1+Debian13+nmu1
ii  multiarch-support                    2.19-18+deb8u4
ii  procps                               2:3.3.9-9
ii  python                               2.7.9-1
ii  python-dnspython                     1.12.0-1
ii  python-ntdb                          1.0-5
ii  python-samba                         2:4.2.10+dfsg-0+deb8u2
pn  python2.7:any                        <none>
ii  samba-common                         2:4.2.10+dfsg-0+deb8u2
ii  samba-common-bin                     2:4.2.10+dfsg-0+deb8u2
ii  samba-dsdb-modules                   2:4.2.10+dfsg-0+deb8u2
ii  samba-libs                           2:4.2.10+dfsg-0+deb8u2
ii  tdb-tools                            1.3.6-0+deb8u1
ii  update-inetd                         4.43

Versions of packages samba recommends:
pn  attr               <none>
ii  logrotate          3.8.7-1+b1
pn  samba-vfs-modules  <none>

Versions of packages samba suggests:
pn  bind9          <none>
pn  bind9utils     <none>
pn  ctdb           <none>
pn  ldb-tools      <none>
ii  ntp            1:4.2.6.p5+dfsg-7+deb8u1
pn  smbldap-tools  <none>
pn  winbind        <none>

-- debconf information:
  samba-common/title:
  samba/run_mode: daemons