netdev - [for-next 2/9] net/mlx5: Avoid NULL pointer dereference on steering cleanup

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Message-Id: <20171006233749.25545-3-saeedm@mellanox.com>
Date:   Fri,  6 Oct 2017 16:37:42 -0700
From:   Saeed Mahameed <saeedm@...lanox.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Doug Ledford <dledford@...hat.com>
Cc:     netdev@...r.kernel.org, linux-rdma@...r.kernel.org,
        Leon Romanovsky <leonro@...lanox.com>,
        Maor Gottlieb <maorg@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: [for-next 2/9] net/mlx5: Avoid NULL pointer dereference on steering cleanup

From: Maor Gottlieb <maorg@...lanox.com>

On cleanup, when the node is the last child of parent then it calls to
tree_put_node on the parent, if the parent's reference count
is decremented to 0 (for e.g. when deleting last destination of FTE)
then we free the parent as well and vice versa. In such a case
we will try to free the parent node again.
Increment the parent reference count before cleaning it's children
will prevent implicit release of the parent object.

Fixes: 0da2d66666d3 ('net/mlx5: Properly remove all steering objects')
signed-off-by: Maor Gottlieb <maorg@...lanox.com>
Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/fs_core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
index 6ffe925..f390828 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
@@ -2068,8 +2068,10 @@ static void clean_tree(struct fs_node *node)
 		struct fs_node *iter;
 		struct fs_node *temp;
 
+		tree_get_node(node);
 		list_for_each_entry_safe(iter, temp, &node->children, list)
 			clean_tree(iter);
+		tree_put_node(node);
 		tree_remove_node(node);
 	}
 }
-- 
1.8.3.1