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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, David Ahern <dsahern@gmail.com>,
        wenxu <wenxu@ucloud.cn>, "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 5.4 14/43] ipv4: Initialize flowi4_multipath_hash in data path
Date:   Fri, 25 Sep 2020 14:48:26 +0200
Message-Id: <20200925124725.711828973@linuxfoundation.org>
In-Reply-To: <20200925124723.575329814@linuxfoundation.org>
References: <20200925124723.575329814@linuxfoundation.org>
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From: David Ahern <dsahern@gmail.com>

[ Upstream commit 1869e226a7b3ef75b4f70ede2f1b7229f7157fa4 ]

flowi4_multipath_hash was added by the commit referenced below for
tunnels. Unfortunately, the patch did not initialize the new field
for several fast path lookups that do not initialize the entire flow
struct to 0. Fix those locations. Currently, flowi4_multipath_hash
is random garbage and affects the hash value computed by
fib_multipath_hash for multipath selection.

Fixes: 24ba14406c5c ("route: Add multipath_hash in flowi_common to make user-define hash")
Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: wenxu <wenxu@ucloud.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 include/net/flow.h      |    1 +
 net/core/filter.c       |    1 +
 net/ipv4/fib_frontend.c |    1 +
 net/ipv4/route.c        |    1 +
 4 files changed, 4 insertions(+)

--- a/include/net/flow.h
+++ b/include/net/flow.h
@@ -116,6 +116,7 @@ static inline void flowi4_init_output(st
 	fl4->saddr = saddr;
 	fl4->fl4_dport = dport;
 	fl4->fl4_sport = sport;
+	fl4->flowi4_multipath_hash = 0;
 }
 
 /* Reset some input parameters after previous lookup */
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4650,6 +4650,7 @@ static int bpf_ipv4_fib_lookup(struct ne
 	fl4.saddr = params->ipv4_src;
 	fl4.fl4_sport = params->sport;
 	fl4.fl4_dport = params->dport;
+	fl4.flowi4_multipath_hash = 0;
 
 	if (flags & BPF_FIB_LOOKUP_DIRECT) {
 		u32 tbid = l3mdev_fib_table_rcu(dev) ? : RT_TABLE_MAIN;
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -372,6 +372,7 @@ static int __fib_validate_source(struct
 	fl4.flowi4_tun_key.tun_id = 0;
 	fl4.flowi4_flags = 0;
 	fl4.flowi4_uid = sock_net_uid(net, NULL);
+	fl4.flowi4_multipath_hash = 0;
 
 	no_addr = idev->ifa_list == NULL;
 
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2104,6 +2104,7 @@ static int ip_route_input_slow(struct sk
 	fl4.daddr = daddr;
 	fl4.saddr = saddr;
 	fl4.flowi4_uid = sock_net_uid(net, NULL);
+	fl4.flowi4_multipath_hash = 0;
 
 	if (fib4_rules_early_flow_dissect(net, skb, &fl4, &_flkeys)) {
 		flkeys = &_flkeys;