[PATCH 5.18 113/158] ipv4: Fix data-races around sysctl_fib_multipath_hash_policy.

Greg Kroah-Hartman
2022-07-27T17:41:31Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 7998c12a08c97cc26660532c9f90a34bd7d8da5a ]

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

Fixes: bf4e0a3db97e ("net: ipv4: add support for ECMP hash policy choice")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.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 | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
index 994bd2e14e55..6bcb0f1b0816 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -10263,7 +10263,7 @@ static void mlxsw_sp_mp4_hash_init(struct mlxsw_sp *mlxsw_sp,
unsigned long *fields = config->fields;
u32 hash_fields;

- switch (net->ipv4.sysctl_fib_multipath_hash_policy) {
+ switch (READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_policy)) {
case 0:
mlxsw_sp_mp4_hash_outer_addr(config);
break;
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 8363e575c455..907cb11cbea5 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2047,7 +2047,7 @@ int fib_multipath_hash(const struct net *net, const struct flowi4 *fl4,
struct flow_keys hash_keys;
u32 mhash = 0;

- switch (net->ipv4.sysctl_fib_multipath_hash_policy) {
+ switch (READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_policy)) {
case 0:
memset(&hash_keys, 0, sizeof(hash_keys));
hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
--
2.35.1