netdev - [PATCH 3.16 304/366] netlink: Do not subscribe to non-existent groups

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Date:   Sun, 11 Nov 2018 19:49:05 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Herbert Xu" <herbert@...dor.apana.org.au>,
        "Dmitry Safonov" <dima@...sta.com>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        "Steffen Klassert" <steffen.klassert@...unet.com>
Subject: [PATCH 3.16 304/366] netlink: Do not subscribe to non-existent groups

3.16.61-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Dmitry Safonov <dima@...sta.com>

commit 7acf9d4237c46894e0fa0492dd96314a41742e84 upstream.

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@...emloft.net>
Cc: Herbert Xu <herbert@...dor.apana.org.au>
Cc: Steffen Klassert <steffen.klassert@...unet.com>
Cc: netdev@...r.kernel.org
Signed-off-by: Dmitry Safonov <dima@...sta.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/netlink/af_netlink.c | 1 +
 1 file changed, 1 insertion(+)

--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -927,6 +927,7 @@ static int netlink_bind(struct socket *s
 		if (err)
 			return err;
 	}
+	groups &= (1UL << nlk->ngroups) - 1;
 
 	if (nlk->portid)
 		if (nladdr->nl_pid != nlk->portid)