[PATCH wireless] wifi: rt2x00: avoid full teardown before work setup in probe

[Runyu Xiao]

rt2x00lib_probe_dev() uses the full rt2x00lib_remove_dev() teardown for
all probe failures. However, drv_data allocation and workqueue allocation
can fail before intf_work, autowakeup_work and sleep_work have been
initialized.

Do not enter the full remove path until the probe has reached the point
where those work items are set up. Return directly for drv_data allocation
failure, and use a small early cleanup path for workqueue allocation
failure.

This issue was found by our static analysis tool and then confirmed by
manual review of rt2x00lib_probe_dev() and rt2x00lib_remove_dev(). The
early probe exits should not call a common teardown path that assumes the
later work setup has already completed.

A QEMU PoC forced alloc_ordered_workqueue() to fail before the work
initializers are reached. The resulting fail path entered
rt2x00lib_remove_dev(), and DEBUG_OBJECTS reported invalid work drains with
rt2x00lib_probe_dev() and rt2x00lib_remove_dev() in the stack.

Fixes: 1ebbc48520a0 ("rt2x00: Introduce concept of driver data in struct rt2x00_dev.")
Fixes: 0439f5367c8d ("rt2x00: Move TX/RX work into dedicated workqueue")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Runyu Xiao <runyu.xiao@xxxxxxxxxx>
---
 drivers/net/wireless/ralink/rt2x00/rt2x00dev.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ralink/rt2x00/rt2x00dev.c b/drivers/net/wireless/ralink/rt2x00/rt2x00dev.c
index f8a6f9c968a1..847b64e586f6 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2x00dev.c
+++ b/drivers/net/wireless/ralink/rt2x00/rt2x00dev.c
@@ -1382,7 +1382,7 @@ int rt2x00lib_probe_dev(struct rt2x00_dev *rt2x00dev)
 			                      GFP_KERNEL);
 		if (!rt2x00dev->drv_data) {
 			retval = -ENOMEM;
-			goto exit;
+			return retval;
 		}
 	}
 
@@ -1416,7 +1416,7 @@ int rt2x00lib_probe_dev(struct rt2x00_dev *rt2x00dev)
 	    alloc_ordered_workqueue("%s", 0, wiphy_name(rt2x00dev->hw->wiphy));
 	if (!rt2x00dev->workqueue) {
 		retval = -ENOMEM;
-		goto exit;
+		goto exit_free_drv_data;
 	}
 
 	INIT_WORK(&rt2x00dev->intf_work, rt2x00lib_intf_scheduled);
@@ -1488,6 +1488,14 @@ int rt2x00lib_probe_dev(struct rt2x00_dev *rt2x00dev)
 exit:
 	rt2x00lib_remove_dev(rt2x00dev);
 
+	return retval;
+
+exit_free_drv_data:
+	clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
+
+	kfree(rt2x00dev->drv_data);
+	rt2x00dev->drv_data = NULL;
+
 	return retval;
 }
 EXPORT_SYMBOL_GPL(rt2x00lib_probe_dev);
-- 
2.34.1