Merge tag 'selinux-pr-20181115' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull SELinux fixes from Paul Moore:
 "Two small SELinux fixes for v4.20.

  Ondrej's patch adds a check on user input, and my patch ensures we
  don't look past the end of a buffer.

  Both patches are quite small and pass the selinux-testsuite"

* tag 'selinux-pr-20181115' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: fix non-MLS handling in mls_context_to_sid()
  selinux: check length properly in SCTP bind hook

2 files changed, 10 insertions, 3 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 7ce683259357..a67459eb62d5 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -5318,6 +5318,9 @@ static int selinux_sctp_bind_connect(struct sock *sk, int optname,
         addr_buf = address;
 
         while (walk_size < addrlen) {
+                if (walk_size + sizeof(sa_family_t) > addrlen)
+                        return -EINVAL;
+
                 addr = addr_buf;
                 switch (addr->sa_family) {
                 case AF_UNSPEC:
diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c
index 2fe459df3c85..b7efa2296969 100644
--- a/security/selinux/ss/mls.c
+++ b/security/selinux/ss/mls.c
@@ -245,9 +245,13 @@ int mls_context_to_sid(struct policydb *pol,
         char *rangep[2];
 
         if (!pol->mls_enabled) {
-                if ((def_sid != SECSID_NULL && oldc) || (*scontext) == '\0')
-                        return 0;
-                return -EINVAL;
+                /*
+                 * With no MLS, only return -EINVAL if there is a MLS field
+                 * and it did not come from an xattr.
+                 */
+                if (oldc && def_sid == SECSID_NULL)
+                        return -EINVAL;
+                return 0;
         }
 
         /*