ipv4: Initialize flowi4_multipath_hash in data path

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: 24ba1440 ("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>

include/net/flow.h

@@ -116,6 +116,7 @@ static inline void flowi4_init_output(struct flowi4 *fl4, int oif,
 	fl4->saddr = saddr;
 	fl4->fl4_dport = dport;
 	fl4->fl4_sport = sport;
+	fl4->flowi4_multipath_hash = 0;
 }
 
 /* Reset some input parameters after previous lookup */

net/core/filter.c

@@ -4838,6 +4838,7 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
 	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;

net/ipv4/fib_frontend.c

@@ -362,6 +362,7 @@ static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
 	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;
 

net/ipv4/route.c

@@ -2147,6 +2147,7 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 	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;