linux-kernel - [PATCH net] net/mlx5e: fix double free of encap

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Message-Id: <20231025032712.79026-1-dust.li@linux.alibaba.com>
Date:   Wed, 25 Oct 2023 11:27:12 +0800
From:   Dust Li <dust.li@...ux.alibaba.com>
To:     Saeed Mahameed <saeedm@...dia.com>,
        Leon Romanovsky <leon@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     Dust Li <dust.li@...ux.alibaba.com>, netdev@...r.kernel.org,
        linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        Cruz Zhao <cruzzhao@...ux.alibaba.com>,
        Tianchen Ding <dtcccc@...ux.alibaba.com>
Subject: [PATCH net] net/mlx5e: fix double free of encap_header

When mlx5_packet_reformat_alloc() fails, the encap_header allocated in
mlx5e_tc_tun_create_header_ipv4{6} will be released within it. However,
e->encap_header is already set to the previously freed encap_header
before mlx5_packet_reformat_alloc(). As a result, the later
mlx5e_encap_put() will free e->encap_header again, causing a double free
issue.

mlx5e_encap_put()
    --> mlx5e_encap_dealloc()
        --> kfree(e->encap_header)

This happens when cmd: MLX5_CMD_OP_ALLOC_PACKET_REFORMAT_CONTEXT fail.

This patch fix it by not setting e->encap_header until
mlx5_packet_reformat_alloc() success.

Fixes: d589e785baf5e("net/mlx5e: Allow concurrent creation of encap entries")
Reported-by: Cruz Zhao <cruzzhao@...ux.alibaba.com>
Reported-by: Tianchen Ding <dtcccc@...ux.alibaba.com>
Signed-off-by: Dust Li <dust.li@...ux.alibaba.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en/tc_tun.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/tc_tun.c b/drivers/net/ethernet/mellanox/mlx5/core/en/tc_tun.c
index 00a04fdd756f..8bca696b6658 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/tc_tun.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/tc_tun.c
@@ -300,9 +300,6 @@ int mlx5e_tc_tun_create_header_ipv4(struct mlx5e_priv *priv,
 	if (err)
 		goto destroy_neigh_entry;
 
-	e->encap_size = ipv4_encap_size;
-	e->encap_header = encap_header;
-
 	if (!(nud_state & NUD_VALID)) {
 		neigh_event_send(attr.n, NULL);
 		/* the encap entry will be made valid on neigh update event
@@ -322,6 +319,8 @@ int mlx5e_tc_tun_create_header_ipv4(struct mlx5e_priv *priv,
 		goto destroy_neigh_entry;
 	}
 
+	e->encap_size = ipv4_encap_size;
+	e->encap_header = encap_header;
 	e->flags |= MLX5_ENCAP_ENTRY_VALID;
 	mlx5e_rep_queue_neigh_stats_work(netdev_priv(attr.out_dev));
 	mlx5e_route_lookup_ipv4_put(&attr);
@@ -568,9 +567,6 @@ int mlx5e_tc_tun_create_header_ipv6(struct mlx5e_priv *priv,
 	if (err)
 		goto destroy_neigh_entry;
 
-	e->encap_size = ipv6_encap_size;
-	e->encap_header = encap_header;
-
 	if (!(nud_state & NUD_VALID)) {
 		neigh_event_send(attr.n, NULL);
 		/* the encap entry will be made valid on neigh update event
@@ -590,6 +586,8 @@ int mlx5e_tc_tun_create_header_ipv6(struct mlx5e_priv *priv,
 		goto destroy_neigh_entry;
 	}
 
+	e->encap_size = ipv6_encap_size;
+	e->encap_header = encap_header;
 	e->flags |= MLX5_ENCAP_ENTRY_VALID;
 	mlx5e_rep_queue_neigh_stats_work(netdev_priv(attr.out_dev));
 	mlx5e_route_lookup_ipv6_put(&attr);
-- 
2.19.1.6.gb485710b