[PATCH 2/2] Bluetooth: hci_core: Handle skb_clone() failure in hci_send_cmd_sync()

[Hans de Goede <johannes.goede@oss.qualcomm.com>]

From: Ibrahim Abdelkader <iabdelka@qti.qualcomm.com>

hci_send_cmd_sync() does not handle the second skb_clone() failure as it
does the first one. At that point the command has already been sent and
HCI_CMD_PENDING is set, so an allocation failure leaves the flag set with
req_skb NULL. The response then matches nothing and the caller blocks for
HCI_INIT_TIMEOUT before getting -ETIMEDOUT, reporting a memory shortage as
a controller timeout.

Clear the flag, cancel the pending request with -ENOMEM so the caller fails
immediately instead of waiting out the timeout, and return -ENOMEM so
hci_cmd_work() does not arm cmd_timer for a request that no longer exists.

Clearing HCI_CMD_PENDING here is safe: all code touching that flag runs
from hdev->workqueue, which is an ordered workqueue, so those paths are
serialised and cannot race. The one exception is the cleanup added by
commit ed516e3f1aa6 ("Bluetooth: hci_sync: Clear HCI_CMD_PENDING when
dropping the last request"), which runs on hci_dev_open_sync() failure and
from hci_dev_close_sync(), and the workqueue is stopped before that runs.

Fixes: 2615fd9a7c25 ("Bluetooth: hci_sync: Fix overwriting request callback")
Signed-off-by: Ibrahim Abdelkader <iabdelka@qti.qualcomm.com>
Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
---
 net/bluetooth/hci_core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 8aeb3024428b..9585b42e7970 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -4092,6 +4092,11 @@ static int hci_send_cmd_sync(struct hci_dev *hdev, struct sk_buff *skb)
 	    !hci_dev_test_and_set_flag(hdev, HCI_CMD_PENDING)) {
 		kfree_skb(hdev->req_skb);
 		hdev->req_skb = skb_clone(hdev->sent_cmd, GFP_KERNEL);
+		if (!hdev->req_skb) {
+			hci_dev_clear_flag(hdev, HCI_CMD_PENDING);
+			hci_cmd_sync_cancel_sync(hdev, ENOMEM);
+			err = -ENOMEM;
+		}
 	}
 
 	return err;
-- 
2.55.0