LU-3095 build: fix 'memory corruption' errors

LU-3095 build: fix 'memory corruption' errors

Fix 'memory corruption' defects found by Coverity version 6.5.1:
Unbounded source buffer (STRING_SIZE)
Passing string of unknown size to function which expects a string
of a particular size.
Write to pointer after free (USE_AFTER_FREE)
Dereferencing freed pointer.
Also fix leak of dentries.

Signed-off-by: Sebastien Buisson <sebastien.buisson@bull.net>
Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Change-Id: I95a1f877025b2e3b58ace7ed86a82330f64c64a3
Reviewed-on: http://review.whamcloud.com/5926
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Li Wei <wei.g.li@intel.com>
Reviewed-by: Faccini Bruno <bruno.faccini@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>