[PATCH 5.15 178/204] ipv4: prevent potential spectre v1 gadget in ip_metrics_convert()

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit 1d1d63b612801b3f0a39b7d4467cad0abd60e5c8 ]

if (!type)
		continue;
	if (type > RTAX_MAX)
		return -EINVAL;
	...
	metrics[type - 1] = val;

@type being used as an array index, we need to prevent
cpu speculation or risk leaking kernel memory content.

Fixes: 6cf9dfd3bd62 ("net: fib: move metrics parsing to a helper")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230120133040.3623463-1-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/ipv4/metrics.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/metrics.c b/net/ipv4/metrics.c
index 25ea6ac44db9..6a1427916c7d 100644
--- a/net/ipv4/metrics.c
+++ b/net/ipv4/metrics.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 #include <linux/netlink.h>
+#include <linux/nospec.h>
 #include <linux/rtnetlink.h>
 #include <linux/types.h>
 #include <net/ip.h>
@@ -28,6 +29,7 @@ static int ip_metrics_convert(struct net *net, struct nlattr *fc_mx,
 			return -EINVAL;
 		}
 
+		type = array_index_nospec(type, RTAX_MAX + 1);
 		if (type == RTAX_CC_ALGO) {
 			char tmp[TCP_CA_NAME_MAX];
 
-- 
2.39.0