[PATCH 5.18 114/158] ipv4: Fix data-races around sysctl_fib_multipath_hash_fields.

Greg Kroah-Hartman
2022-07-27T17:41:42Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ 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@amazon.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 6bcb0f1b0816..c00d6c4ed37c 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -10281,7 +10281,7 @@ 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 907cb11cbea5..02a0a397a2f3 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1928,7 +1928,7 @@ 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))
@@ -1957,7 +1957,7 @@ 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
@@ -2017,7 +2017,7 @@ 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