From: Stephen Smalley <sds@epoch.ncsc.mil>

This patch changes security_context_to_sid to check the length of the
processed security context against the full length of the provided context,
rejecting any further data.
Signed-off-by: Stephen Smalley <sds@epoch.ncsc.mil>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>