linux-kernel - [PATCH 2/2] net: socket: Fix potential spectre v1 gadget in sock_is

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Date:   Fri, 27 Jul 2018 22:43:02 +0000
From:   Jeremy Cline <jcline@...hat.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Jeremy Cline <jcline@...hat.com>, stable@...r.kernel.org
Subject: [PATCH 2/2] net: socket: Fix potential spectre v1 gadget in sock_is_registered

'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@...hat.com>
Cc: stable@...r.kernel.org
Signed-off-by: Jeremy Cline <jcline@...hat.com>
---
 net/socket.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/socket.c b/net/socket.c
index f15d5cbb3ba4..608e29ae6baf 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2672,7 +2672,8 @@ 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)
-- 
2.17.1