commit be67b68d upstream

Defensively check that the field to be worked on is not NULL.
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@kernel.org
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Willy Tarreau <w@1wt.eu>