From fd9af86da3df9cd3f6eff81acaf6a6c4c804a501 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Fri, 20 Jan 2023 21:31:40 +0800
Subject: [PATCH] ipv4: prevent potential spectre v1 gadget in
 fib_metrics_match()

ANBZ: #19816

commit 7f9828fb1f688210e681268490576f0ca65c322a stable.

commit 5e9398a26a92fc402d82ce1f97cc67d832527da0 upstream.

if (!type)
        continue;
    if (type > RTAX_MAX)
        return false;
    ...
    fi_val = fi->fib_metrics->metrics[type - 1];

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

Fixes: 5f9ae3d9e7e4 ("ipv4: do metrics match when looking up and deleting a route")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230120133140.3624204-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Fixes: CVE-2023-52996
Signed-off-by: Xiao Long <xiaolong@openanolis.org>
Signed-off-by: Philo Lu <lulie@linux.alibaba.com>
---
 net/ipv4/fib_semantics.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index eefc346df752..4fb03094ab78 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -30,6 +30,7 @@
 #include <linux/slab.h>
 #include <linux/netlink.h>
 #include <linux/hash.h>
+#include <linux/nospec.h>
 
 #include <net/arp.h>
 #include <net/ip.h>
@@ -1019,6 +1020,7 @@ bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
 		if (type > RTAX_MAX)
 			return false;
 
+		type = array_index_nospec(type, RTAX_MAX + 1);
 		if (type == RTAX_CC_ALGO) {
 			char tmp[TCP_CA_NAME_MAX];
 			bool ecn_ca = false;
-- 
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