[PATCH] netlink: Do not subscribe to non-existent groups

[PATCH] netlink: Do not subscribe to non-existent groups

[Dmitry Safonov]

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>
---
 net/netlink/af_netlink.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 393573a99a5a..ac805caed2e2 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1008,6 +1008,7 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
 		if (err)
 			return err;
 	}
+	groups &= (1UL << nlk->ngroups) - 1;
 
 	bound = nlk->bound;
 	if (bound) {
-- 
2.13.6

Re: [PATCH] netlink: Do not subscribe to non-existent groups

[David Miller]

From: Dmitry Safonov <dima@arista.com>
Date: Fri, 27 Jul 2018 16:54:44 +0100

> 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>

Applied and queued up for -stable, thanks.