[PATCH 5.15 118/201] ipv4: Fix data-races around sysctl_fib_multipath_hash_fields.

[Greg Kroah-Hartman]

From: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>

[ Upstream commit 8895a9c2ac76fb9d3922fed4fe092c8ec5e5cccc ]

While reading sysctl_fib_multipath_hash_fields, it can be changed
concurrently.  Thus, we need to add READ_ONCE() to its readers.

Fixes: ce5c9c20d364 ("ipv4: Add a sysctl to control multipath hash fields")
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Reviewed-by: Ido Schimmel <idosch@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 2 +-
 net/ipv4/route.c                                      | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
index 6cdf0e232b1c..55de90d5ae59 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -9606,7 +9606,7 @@ static void mlxsw_sp_mp4_hash_init(struct mlxsw_sp *mlxsw_sp,
 		mlxsw_sp_mp_hash_inner_l3(config);
 		break;
 	case 3:
-		hash_fields = net->ipv4.sysctl_fib_multipath_hash_fields;
+		hash_fields = READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_fields);
 		/* Outer */
 		MLXSW_SP_MP_HASH_HEADER_SET(headers, IPV4_EN_NOT_TCP_NOT_UDP);
 		MLXSW_SP_MP_HASH_HEADER_SET(headers, IPV4_EN_TCP_UDP);
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index ade6cb309c40..ca59b61fd3a3 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1929,7 +1929,7 @@ static u32 fib_multipath_custom_hash_outer(const struct net *net,
 					   const struct sk_buff *skb,
 					   bool *p_has_inner)
 {
-	u32 hash_fields = net->ipv4.sysctl_fib_multipath_hash_fields;
+	u32 hash_fields = READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_fields);
 	struct flow_keys keys, hash_keys;
 
 	if (!(hash_fields & FIB_MULTIPATH_HASH_FIELD_OUTER_MASK))
@@ -1958,7 +1958,7 @@ static u32 fib_multipath_custom_hash_inner(const struct net *net,
 					   const struct sk_buff *skb,
 					   bool has_inner)
 {
-	u32 hash_fields = net->ipv4.sysctl_fib_multipath_hash_fields;
+	u32 hash_fields = READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_fields);
 	struct flow_keys keys, hash_keys;
 
 	/* We assume the packet carries an encapsulation, but if none was
@@ -2018,7 +2018,7 @@ static u32 fib_multipath_custom_hash_skb(const struct net *net,
 static u32 fib_multipath_custom_hash_fl4(const struct net *net,
 					 const struct flowi4 *fl4)
 {
-	u32 hash_fields = net->ipv4.sysctl_fib_multipath_hash_fields;
+	u32 hash_fields = READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_fields);
 	struct flow_keys hash_keys;
 
 	if (!(hash_fields & FIB_MULTIPATH_HASH_FIELD_OUTER_MASK))
-- 
2.35.1