[PATCH 4.4 020/149] mlxsw: core: Increase scope of RCU read-side critical section

[Greg Kroah-Hartman]

From: Ido Schimmel <ido...@mellanox.com>

[ Upstream commit 7d8e8f3433dc8d1dc87c1aabe73a154978fb4c4d ]

The lifetime of the Rx listener item ('rxl_item') is managed using RCU,
but is dereferenced outside of RCU read-side critical section, which can
lead to a use-after-free.

Fix this by increasing the scope of the RCU read-side critical section.

Fixes: 93c1edb27f9e ("mlxsw: Introduce Mellanox switch driver core")
Signed-off-by: Ido Schimmel <ido...@mellanox.com>
Reviewed-by: Jiri Pirko <j...@mellanox.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 drivers/net/ethernet/mellanox/mlxsw/core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/core.c 
b/drivers/net/ethernet/mellanox/mlxsw/core.c
index 97f0d93caf994..085aaad902937 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/core.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/core.c
@@ -1208,9 +1208,10 @@ void mlxsw_core_skb_receive(struct mlxsw_core 
*mlxsw_core, struct sk_buff *skb,
                        break;
                }
        }
-       rcu_read_unlock();
-       if (!found)
+       if (!found) {
+               rcu_read_unlock();
                goto drop;
+       }
 
        pcpu_stats = this_cpu_ptr(mlxsw_core->pcpu_stats);
        u64_stats_update_begin(&pcpu_stats->syncp);
@@ -1221,6 +1222,7 @@ void mlxsw_core_skb_receive(struct mlxsw_core 
*mlxsw_core, struct sk_buff *skb,
        u64_stats_update_end(&pcpu_stats->syncp);
 
        rxl->func(skb, local_port, rxl_item->priv);
+       rcu_read_unlock();
        return;
 
 drop:
-- 
2.25.1