[PATCH v2 1/1] Bluetooth: mgmt: Dequeue pending mesh_send_sync entries on cancel

[Lee Jones]

In send_cancel(), pending mesh_tx objects are removed from the
hdev->mesh_pending list and freed via mesh_send_complete().  However, if
a mesh transmission was already queued onto hdev->cmd_sync_work_list via
mesh_next(), the queued entry retains a raw pointer to mesh_tx.

When hci_cmd_sync_work later processes the entry, it attempts to execute
mesh_send_sync and its destroy callback mesh_send_start_complete using
the already freed mesh_tx pointer, leading to a use-after-free.

Fix this by invoking hci_cmd_sync_dequeue() for mesh_send_sync on the
target mesh_tx before completing it.  If the entry is found and dequeued,
its destroy callback will complete and free the object; otherwise,
mesh_send_complete() is called directly.

Additionally, ensure the transmission queue advances after cancellation
or errors.  In mesh_send_start_complete(), call mesh_next() on error
unless err is -ECANCELED, because hci_cmd_sync_dequeue() holds
hdev->cmd_sync_work_lock and calling mesh_next() synchronously would
deadlock.  Instead, advance the queue in send_cancel() once the lock is
released and if no transmission is in progress.

Fixes: b338d91703fa ("Bluetooth: Implement support for Mesh")
Signed-off-by: Lee Jones <lee@xxxxxxxxxx>
---

v1 -> v2:
  - Advance mesh queue in send_cancel() once cmd_sync_work_lock is released
  - Advance mesh queue on error in mesh_send_start_complete(), skipping -ECANCELED to avoid self-deadlock

 net/bluetooth/mgmt.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 0b2d130e492c..55ccf9b714af 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -2290,6 +2290,8 @@ static void mesh_send_start_complete(struct hci_dev *hdev, void *data, int err)
 		hci_dev_clear_flag(hdev, HCI_MESH_SENDING);
 		/* Send Complete Error Code for handle */
 		mesh_send_complete(hdev, mesh_tx, false);
+		if (err != -ECANCELED)
+			mesh_next(hdev, NULL, 0);
 		return;
 	}
 
@@ -2399,20 +2401,29 @@ static int send_cancel(struct hci_dev *hdev, void *data)
 		do {
 			mesh_tx = mgmt_mesh_next(hdev, cmd->sk);
 
-			if (mesh_tx)
-				mesh_send_complete(hdev, mesh_tx, false);
+			if (mesh_tx) {
+				if (!hci_cmd_sync_dequeue(hdev, mesh_send_sync,
+							  mesh_tx, NULL))
+					mesh_send_complete(hdev, mesh_tx, false);
+			}
 		} while (mesh_tx);
 	} else {
 		mesh_tx = mgmt_mesh_find(hdev, cancel->handle);
 
-		if (mesh_tx && mesh_tx->sk == cmd->sk)
-			mesh_send_complete(hdev, mesh_tx, false);
+		if (mesh_tx && mesh_tx->sk == cmd->sk) {
+			if (!hci_cmd_sync_dequeue(hdev, mesh_send_sync,
+						  mesh_tx, NULL))
+				mesh_send_complete(hdev, mesh_tx, false);
+		}
 	}
 
 	mgmt_cmd_complete(cmd->sk, hdev->id, MGMT_OP_MESH_SEND_CANCEL,
 			  0, NULL, 0);
 	mgmt_pending_free(cmd);
 
+	if (!hci_dev_test_flag(hdev, HCI_MESH_SENDING))
+		mesh_next(hdev, NULL, 0);
+
 	return 0;
 }
 
-- 
2.55.0.1007.g17ff1f9808-goog