Subject: [net 05/12] net/mlx5e: Destroy page pool after XDP SQ to fix use-after-free

From: Saeed Mahameed <[email-masked]>
Date: Mon, 9 Aug 2021 20:59:16 -0700

From: Maxim Mikityanskiy <[email-masked]>

mlx5e_close_xdpsq does the cleanup: it calls mlx5e_free_xdpsq_descs to
free the outstanding descriptors, which relies on
mlx5e_page_release_dynamic and page_pool_release_page. However,
page_pool_destroy is already called by this point, because
mlx5e_close_rq runs before mlx5e_close_xdpsq.

This commit fixes the use-after-free by swapping mlx5e_close_xdpsq and
mlx5e_close_rq.

The commit cited below started calling page_pool_destroy directly from
the driver. Previously, the page pool was destroyed under a call_rcu
from xdp_rxq_info_unreg_mem_model, which would defer the deallocation
until after the XDPSQ is cleaned up.

Fixes: 1da4bbeffe41 ("net: core: page_pool: add user refcnt and reintroduce page_pool_destroy")
Signed-off-by: Maxim Mikityanskiy <[email-masked]>
Reviewed-by: Tariq Toukan <[email-masked]>
Signed-off-by: Saeed Mahameed <[email-masked]>
---
 .../net/ethernet/mellanox/mlx5/core/en_main.c | 20 +++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 37c440837945..fd250f7bcd88 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -1891,30 +1891,30 @@ static int mlx5e_open_queues(struct mlx5e_channel *c,
 	if (err)
 		goto err_close_icosq;
 
+	err = mlx5e_open_rxq_rq(c, params, &cparam->rq);
+	if (err)
+		goto err_close_sqs;
+
 	if (c->xdp) {
 		err = mlx5e_open_xdpsq(c, params, &cparam->xdp_sq, NULL,
 				       &c->rq_xdpsq, false);
 		if (err)
-			goto err_close_sqs;
+			goto err_close_rq;
 	}
 
-	err = mlx5e_open_rxq_rq(c, params, &cparam->rq);
-	if (err)
-		goto err_close_xdp_sq;
-
 	err = mlx5e_open_xdpsq(c, params, &cparam->xdp_sq, NULL, &c->xdpsq, true);
 	if (err)
-		goto err_close_rq;
+		goto err_close_xdp_sq;
 
 	return 0;
 
-err_close_rq:
-	mlx5e_close_rq(&c->rq);
-
 err_close_xdp_sq:
 	if (c->xdp)
 		mlx5e_close_xdpsq(&c->rq_xdpsq);
 
+err_close_rq:
+	mlx5e_close_rq(&c->rq);
+
 err_close_sqs:
 	mlx5e_close_sqs(c);
 
@@ -1949,9 +1949,9 @@ static int mlx5e_open_queues(struct mlx5e_channel *c,
 static void mlx5e_close_queues(struct mlx5e_channel *c)
 {
 	mlx5e_close_xdpsq(&c->xdpsq);
-	mlx5e_close_rq(&c->rq);
 	if (c->xdp)
 		mlx5e_close_xdpsq(&c->rq_xdpsq);
+	mlx5e_close_rq(&c->rq);
 	mlx5e_close_sqs(c);
 	mlx5e_close_icosq(&c->icosq);
 	mlx5e_close_icosq(&c->async_icosq);
-- 
2.31.1