[PATCH 4.19 162/205] selinux: check length properly in SCTP bind hook

[Greg Kroah-Hartman]

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

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

From: Ondrej Mosnacek <omosnace@xxxxxxxxxx>

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 <cai@xxxxxx>
Fixes: d452930fd3b9 ("selinux: Add SCTP support")
Cc: <stable@xxxxxxxxxxxxxxx> # 4.17+
Cc: Richard Haines <richard_c_haines@xxxxxxxxxxxxxx>
Signed-off-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
Tested-by: Qian Cai <cai@xxxxxx>
Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -5318,6 +5318,9 @@ 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: