BugLink: http://bugs.launchpad.net/bugs/1615620

commit 33baefe5 upstream.

krealloc() doesn't work always properly with __GFP_ZERO flag as
expected.  For clearing the reallocated area, we need to clear
explicitly instead.
Reported-by: Joe Perches <joe@perches.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>