[PATCH 4.9 09/32] netlink: Do not subscribe to non-existent groups

Greg Kroah-Hartman
2018-08-04T09:06:10Z

From: Dmitry Safonov <dima@arista.com>

[ Upstream commit 7acf9d4237c46894e0fa0492dd96314a41742e84 ]

Make ABI more strict about subscribing to group > ngroups.
Code doesn't check for that and it looks bogus.
(one can subscribe to non-existing group)
Still, it's possible to bind() to all possible groups with (-1)

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: netdev@vger.kernel.org
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/netlink/af_netlink.c | 1 +
1 file changed, 1 insertion(+)

--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -983,6 +983,7 @@ static int netlink_bind(struct socket *s
if (err)
return err;
}
+ groups &= (1UL << nlk->ngroups) - 1;

bound = nlk->bound;
if (bound) {