ipv4: prevent potential spectre v1 gadget in fib_metrics_match()

stable inclusion
from stable-v5.10.166
commit 7f9828fb1f688210e681268490576f0ca65c322a
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7TH9O

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7f9828fb1f688210e681268490576f0ca65c322a

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

[ Upstream commit 5e9398a2 ]

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: 5f9ae3d9 ("ipv4: do metrics match when looking up and deleting a route")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230120133140.3624204-1-edumazet@google.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: Nsanglipeng <sanglipeng1@jd.com>

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>
@@ -1021,6 +1022,7 @@ 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;