From: Andrey Vatoropin <redacted>

The function __mlx5_lag_dev_add_mdev() attempts to allocate memory for the
pointer ldev by calling the function mlx5_lag_dev_alloc(). If the memory
allocation fails, mlx5_lag_dev_alloc() returns NULL and the
__mlx5_lag_dev_add_mdev() returns 0. Later in the debugfs handlers there is
an attempt to dereference the ldev pointer.

Change the return value to "-ENOMEM" to avoid NULL pointer using. When
"-ENOMEM" is returned __mlx5_lag_dev_add_mdev() will attempt to
reallocate memory for ldev after a sleep interval.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: cac1eb2cf2e3 ("net/mlx5: Lag, properly lock eswitch if needed")
Cc: stable@vger.kernel.org
Signed-off-by: Andrey Vatoropin <redacted>
---
 drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c
index a459a30f36ca..6e914472a2d7 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c

@@ -1392,7 +1392,7 @@ static int __mlx5_lag_dev_add_mdev(struct mlx5_core_dev *dev)
 		ldev = mlx5_lag_dev_alloc(dev);
 		if (!ldev) {
 			mlx5_core_err(dev, "Failed to alloc lag dev\n");
-			return 0;
+			return -ENOMEM;
 		}
 		mlx5_ldev_add_mdev(ldev, dev);
 		return 0;

-- 
2.43.0