mm/mempolicy.c: fix error handling in set_mempolicy and mbind.

In the case that compat_get_bitmap fails we do not want to copy the
bitmap to the user as it will contain uninitialized stack data and leak
sensitive data.
Change-Id: I4f66a1c3ef7e616d06d3301b145973ed8cd9e449
Signed-off-by: Chris Salls <salls@cs.ucsb.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Git-commit: cf01fb9985e8deb25ccf0ea54d916b8871ae0e62
Git-repo:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Arun KS <arunks@codeaurora.org>