[PATCH 3.16 085/305] net/mlx4_core: Fix access to uninitialized index

[Ben Hutchings]

3.16.37-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Tariq Toukan <tariqt@xxxxxxxxxxxx>

commit 2bb07e155bb3e0c722c806723f737cf8020961ef upstream.

Prevent using uninitialized or negative index when handling
steering entries.

Fixes: b12d93d63c32 ('mlx4: Add support for promiscuous mode in the new steering model.')
Signed-off-by: Tariq Toukan <tariqt@xxxxxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/net/ethernet/mellanox/mlx4/mcg.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx4/mcg.c
+++ b/drivers/net/ethernet/mellanox/mlx4/mcg.c
@@ -953,7 +953,7 @@ int mlx4_qp_attach_common(struct mlx4_de
 	struct mlx4_cmd_mailbox *mailbox;
 	struct mlx4_mgm *mgm;
 	u32 members_count;
-	int index, prev;
+	int index = -1, prev;
 	int link = 0;
 	int i;
 	int err;
@@ -1032,7 +1032,7 @@ int mlx4_qp_attach_common(struct mlx4_de
 		goto out;
 
 out:
-	if (prot == MLX4_PROT_ETH) {
+	if (prot == MLX4_PROT_ETH && index != -1) {
 		/* manage the steering entry for promisc mode */
 		if (new_entry)
 			new_steering_entry(dev, port, steer, index, qp->qpn);