[PATCH 4.18 29/35] net: sock_diag: Fix spectre v1 gadget in __sock_diag_cmd()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

From: Jeremy Cline <jcline@redhat.com>

[ Upstream commit 66b51b0a0341fd42ce657739bdae0561b0410a85 ]

req->sdiag_family is a user-controlled value that's used as an array
index. Sanitize it after the bounds check to avoid speculative
out-of-bounds array access.

This also protects the sock_is_registered() call, so this removes the
sanitize call there.

Fixes: e978de7a6d38 ("net: socket: Fix potential spectre v1 gadget in sock_is_registered")
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: konrad.wilk@oracle.com
Cc: jamie.iles@oracle.com
Cc: liran.alon@oracle.com
Cc: stable@vger.kernel.org
Signed-off-by: Jeremy Cline <jcline@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/core/sock_diag.c |    2 ++
 net/socket.c         |    3 +--
 2 files changed, 3 insertions(+), 2 deletions(-)

--- a/net/core/sock_diag.c
+++ b/net/core/sock_diag.c
@@ -10,6 +10,7 @@
 #include <linux/kernel.h>
 #include <linux/tcp.h>
 #include <linux/workqueue.h>
+#include <linux/nospec.h>
 
 #include <linux/inet_diag.h>
 #include <linux/sock_diag.h>
@@ -218,6 +219,7 @@ static int __sock_diag_cmd(struct sk_buf
 
 	if (req->sdiag_family >= AF_MAX)
 		return -EINVAL;
+	req->sdiag_family = array_index_nospec(req->sdiag_family, AF_MAX);
 
 	if (sock_diag_handlers[req->sdiag_family] == NULL)
 		sock_load_diag_module(req->sdiag_family, 0);
--- a/net/socket.c
+++ b/net/socket.c
@@ -2690,8 +2690,7 @@ EXPORT_SYMBOL(sock_unregister);
 
 bool sock_is_registered(int family)
 {
-	return family < NPROTO &&
-		rcu_access_pointer(net_families[array_index_nospec(family, NPROTO)]);
+	return family < NPROTO && rcu_access_pointer(net_families[family]);
 }
 
 static int __init sock_init(void)