4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ondrej Mosnacek <omosnace@redhat.com>

commit c138325fb8713472d5a0c3c7258b9131bab40725 upstream.

selinux_sctp_bind_connect() must verify if the address buffer has
sufficient length before accessing the 'sa_family' field. See
__sctp_connect() for a similar check.

The length of the whole address ('len') is already checked in the
callees.

Reported-by: Qian Cai <redacted>
Fixes: d452930fd3b9 ("selinux: Add SCTP support")
Cc: <redacted> # 4.17+
Cc: Richard Haines <redacted>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Tested-by: Qian Cai <redacted>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 security/selinux/hooks.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c

@@ -5306,6 +5306,9 @@ static int selinux_sctp_bind_connect(str
 	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: