net: socket: Fix potential spectre v1 gadget in sock_is_registered

jeremycline · gregkh · commit 82d0d07a25eb · 2018-08-06T16:18:20.000+02:00
commit e978de7 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@redhat.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>
diff --git 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)

Original file line number	Diff line number	Diff line change
`@@ -2694,7 +2694,8 @@ EXPORT_SYMBOL(sock_unregister);`
`2694`	`2694`
`2695`	`2695`	`bool sock_is_registered(int family)`
`2696`	`2696`	`{`
`2697`		`- return family < NPROTO && rcu_access_pointer(net_families[family]);`
	`2697`	`+ return family < NPROTO &&`
	`2698`	`+ rcu_access_pointer(net_families[array_index_nospec(family, NPROTO)]);`
`2698`	`2699`	`}`
`2699`	`2700`
`2700`	`2701`	`static int __init sock_init(void)`