selinux: check length properly in SCTP bind hook

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@gmx.us>
Fixes: d452930fd3b9 ("selinux: Add SCTP support")
Cc: <stable@vger.kernel.org> # 4.17+
Cc: Richard Haines <richard_c_haines@btinternet.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Tested-by: Qian Cai <cai@gmx.us>
Signed-off-by: Paul Moore <paul@paul-moore.com>

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 18b98b5e1e3c46d1256ad1ffacff6ebc711beed3..fe251c6f09f104dcfdd70ee83c72c295f37b390a 100644 (file)
--- 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: