[PATCH net v4] net/mlx5e: fix a double-free in arfs_create_groups

[PATCH net v4] net/mlx5e: fix a double-free in arfs_create_groups

[Zhipeng Lu]

When `in` allocated by kvzalloc fails, arfs_create_groups will free
ft->g and return an error. However, arfs_create_table, the only caller of
arfs_create_groups, will hold this error and call to
mlx5e_destroy_flow_table, in which the ft->g will be freed again.

Fixes: 1cabe6b0965e ("net/mlx5e: Create aRFS flow tables")
Signed-off-by: Zhipeng Lu <alexious@zju.edu.cn>
---
Changelog:

v2: free ft->g just in arfs_create_groups with a unwind ladder.
v3: split the allocation of ft->g and in. Rename the error label.
    remove some refector change in v2.
v4: correct some space issue.
---
 .../net/ethernet/mellanox/mlx5/core/en_arfs.c | 26 +++++++++++--------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_arfs.c b/drivers/net/ethernet/mellanox/mlx5/core/en_arfs.c
index bb7f86c993e5..e66f486faafe 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_arfs.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_arfs.c
@@ -254,11 +254,13 @@ static int arfs_create_groups(struct mlx5e_flow_table *ft,
 
 	ft->g = kcalloc(MLX5E_ARFS_NUM_GROUPS,
 			sizeof(*ft->g), GFP_KERNEL);
-	in = kvzalloc(inlen, GFP_KERNEL);
-	if  (!in || !ft->g) {
-		kfree(ft->g);
-		kvfree(in);
+	if (!ft->g)
 		return -ENOMEM;
+
+	in = kvzalloc(inlen, GFP_KERNEL);
+	if (!in) {
+		err = -ENOMEM;
+		goto err_free_g;
 	}
 
 	mc = MLX5_ADDR_OF(create_flow_group_in, in, match_criteria);
@@ -278,7 +280,7 @@ static int arfs_create_groups(struct mlx5e_flow_table *ft,
 		break;
 	default:
 		err = -EINVAL;
-		goto out;
+		goto err_free_in;
 	}
 
 	switch (type) {
@@ -300,7 +302,7 @@ static int arfs_create_groups(struct mlx5e_flow_table *ft,
 		break;
 	default:
 		err = -EINVAL;
-		goto out;
+		goto err_free_in;
 	}
 
 	MLX5_SET_CFG(in, match_criteria_enable, MLX5_MATCH_OUTER_HEADERS);
@@ -309,7 +311,7 @@ static int arfs_create_groups(struct mlx5e_flow_table *ft,
 	MLX5_SET_CFG(in, end_flow_index, ix - 1);
 	ft->g[ft->num_groups] = mlx5_create_flow_group(ft->t, in);
 	if (IS_ERR(ft->g[ft->num_groups]))
-		goto err;
+		goto err_clean_group;
 	ft->num_groups++;
 
 	memset(in, 0, inlen);
@@ -318,18 +320,20 @@ static int arfs_create_groups(struct mlx5e_flow_table *ft,
 	MLX5_SET_CFG(in, end_flow_index, ix - 1);
 	ft->g[ft->num_groups] = mlx5_create_flow_group(ft->t, in);
 	if (IS_ERR(ft->g[ft->num_groups]))
-		goto err;
+		goto err_clean_group;
 	ft->num_groups++;
 
 	kvfree(in);
 	return 0;
 
-err:
+err_clean_group:
 	err = PTR_ERR(ft->g[ft->num_groups]);
 	ft->g[ft->num_groups] = NULL;
-out:
+err_free_in:
 	kvfree(in);
-
+err_free_g:
+	kfree(ft->g);
+	ft->g = NULL;
 	return err;
 }
 
-- 
2.34.1

Re: [PATCH net v4] net/mlx5e: fix a double-free in arfs_create_groups

[Simon Horman]

On Wed, Jan 17, 2024 at 03:17:36PM +0800, Zhipeng Lu wrote:
> When `in` allocated by kvzalloc fails, arfs_create_groups will free
> ft->g and return an error. However, arfs_create_table, the only caller of
> arfs_create_groups, will hold this error and call to
> mlx5e_destroy_flow_table, in which the ft->g will be freed again.
> 
> Fixes: 1cabe6b0965e ("net/mlx5e: Create aRFS flow tables")
> Signed-off-by: Zhipeng Lu <alexious@zju.edu.cn>
> ---
> Changelog:
> 
> v2: free ft->g just in arfs_create_groups with a unwind ladder.
> v3: split the allocation of ft->g and in. Rename the error label.
>     remove some refector change in v2.
> v4: correct some space issue.

Thanks for the updates.

Reviewed-by: Simon Horman <horms@kernel.org>