netdev - [net 6/6] net/mlx5: DR, fix a potential use-after-free bug

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Date:   Thu, 26 Aug 2021 15:18:10 -0700
From:   Saeed Mahameed <saeed@...nel.org>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, Wentao_Liang <Wentao_Liang_g@....com>,
        Saeed Mahameed <saeedm@...dia.com>
Subject: [net 6/6] net/mlx5: DR, fix a potential use-after-free bug

From: Wentao_Liang <Wentao_Liang_g@....com>

In line 849 (#1), "mlx5dr_htbl_put(cur_htbl);" drops the reference to
cur_htbl and may cause cur_htbl to be freed.

However, cur_htbl is subsequently used in the next line, which may result
in an use-after-free bug.

Fix this by calling mlx5dr_err() before the cur_htbl is put.

Signed-off-by: Wentao_Liang <Wentao_Liang_g@....com>
Signed-off-by: Saeed Mahameed <saeedm@...dia.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c
index 43356fad53de..ffdfb5a94b14 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c
@@ -846,9 +846,9 @@ dr_rule_handle_ste_branch(struct mlx5dr_rule *rule,
 			new_htbl = dr_rule_rehash(rule, nic_rule, cur_htbl,
 						  ste_location, send_ste_list);
 			if (!new_htbl) {
-				mlx5dr_htbl_put(cur_htbl);
 				mlx5dr_err(dmn, "Failed creating rehash table, htbl-log_size: %d\n",
 					   cur_htbl->chunk_size);
+				mlx5dr_htbl_put(cur_htbl);
 			} else {
 				cur_htbl = new_htbl;
 			}
-- 
2.31.1