Patch "net/mlx4_core: Use-after-free causes a resource leak in flow-steering detach" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

net/mlx4_core: Use-after-free causes a resource leak in flow-steering detach

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
net-mlx4_core-use-after-free-causes-a-resource-leak-in-flow-steering-detach.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Jack Morgenstein <[email protected]>
Date: Thu, 29 Dec 2016 18:37:09 +0200
Subject: net/mlx4_core: Use-after-free causes a resource leak in flow-steering detach

From: Jack Morgenstein <[email protected]>

[ Upstream commit 3b01fe7f91c8e4f9afc4fae3c5af72c14958d2d8 ]

mlx4_QP_FLOW_STEERING_DETACH_wrapper first removes the steering rule (which results in freeing the rule structure), and then references a field in this struct (the qp number) when releasing the busy-status on the rule's qp.

Since this memory was freed, it could reallocated and changed. Therefore, the qp number in the struct may be incorrect,
so that we are releasing the incorrect qp. This leaves the rule's qp in the busy state (and could possibly release an incorrect qp as well).

Fix this by saving the qp number in a local variable, for use after removing the steering rule.

---
 drivers/net/ethernet/mellanox/mlx4/resource_tracker.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

@@ -4474,6 +4474,7 @@ int mlx4_QP_FLOW_STEERING_DETACH_wrapper
 	struct res_qp *rqp;
 	struct res_fs_rule *rrule;
 	u64 mirr_reg_id;
+	int qpn;
 
 	if (dev->caps.steering_mode !=
 	    MLX4_STEERING_MODE_DEVICE_MANAGED)

@@ -4490,10 +4491,11 @@ int mlx4_QP_FLOW_STEERING_DETACH_wrapper
 	}
 	mirr_reg_id = rrule->mirr_rule_id;
 	kfree(rrule->mirr_mbox);
+	qpn = rrule->qpn;
 
 	/* Release the rule form busy state before removal */
 	put_res(dev, slave, vhcr->in_param, RES_FS_RULE);
-	err = get_res(dev, slave, rrule->qpn, RES_QP, &rqp);
+	err = get_res(dev, slave, qpn, RES_QP, &rqp);
 	if (err)
 		return err;
 

@@ -4518,7 +4520,7 @@ int mlx4_QP_FLOW_STEERING_DETACH_wrapper
 	if (!err)
 		atomic_dec(&rqp->ref_count);
 out:
-	put_res(dev, slave, rrule->qpn, RES_QP);
+	put_res(dev, slave, qpn, RES_QP);
 	return err;
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/net-mlx4_core-fix-raw-qp-flow-steering-rules-under-sriov.patch queue-4.9/net-mlx4_core-use-after-free-causes-a-resource-leak-in-flow-steering-detach.patch