security: Fix some typos and potential NULL-deref

This patch against the git tree fixes minor typos, some of them possibily
leading to NULL-pointer dereference in rare conditions.

Signed-off-by: Remi Gacogne <rgacogne-github@coredump.fr>
Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
Acked-by: Feng Lu <lu.feng@6wind.com>
5 files changed