[PATCH 4.17 15/31] net: socket: Fix potential spectre v1 gadget in sock_is_registered

[Greg Kroah-Hartman]

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

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

From: Jeremy Cline <jcline@xxxxxxxxxx>

commit e978de7a6d382ec378830ca2cf38e902df0b6d84 upstream.

'family' can be a user-controlled value, so sanitize it after the bounds
check to avoid speculative out-of-bounds access.

Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jeremy Cline <jcline@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/socket.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/socket.c
+++ b/net/socket.c
@@ -2694,7 +2694,8 @@ EXPORT_SYMBOL(sock_unregister);
 
 bool sock_is_registered(int family)
 {
-	return family < NPROTO && rcu_access_pointer(net_families[family]);
+	return family < NPROTO &&
+		rcu_access_pointer(net_families[array_index_nospec(family, NPROTO)]);
 }
 
 static int __init sock_init(void)