linux-kernel - [PATCH v6] Bluetooth: btusb: Fix memory leak in play

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Date:   Thu, 20 Jul 2017 18:53:50 +0800
From:   Jeffy Chen <jeffy.chen@...k-chips.com>
To:     linux-kernel@...r.kernel.org, oneukum@...e.com
Cc:     xiyou.wangcong@...il.com, briannorris@...omium.org,
        dianders@...omium.org, Jeffy Chen <jeffy.chen@...k-chips.com>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Marcel Holtmann <marcel@...tmann.org>,
        Gustavo Padovan <gustavo@...ovan.org>,
        linux-bluetooth@...r.kernel.org
Subject: [PATCH v6] Bluetooth: btusb: Fix memory leak in play_deferred

Currently we are calling usb_submit_urb directly to submit deferred tx
urbs after unanchor them.

So the usb_giveback_urb_bh would failed to unref it in usb_unanchor_urb
and cause memory leak:
unreferenced object 0xffffffc0ce0fa400 (size 256):
...
  backtrace:
    [<ffffffc00034a9a8>] __save_stack_trace+0x48/0x6c
    [<ffffffc00034b088>] create_object+0x138/0x254
    [<ffffffc0009d5504>] kmemleak_alloc+0x58/0x8c
    [<ffffffc000345f78>] __kmalloc+0x1d4/0x2a0
    [<ffffffc0006765bc>] usb_alloc_urb+0x30/0x60
    [<ffffffbffc128598>] alloc_ctrl_urb+0x38/0x120 [btusb]
    [<ffffffbffc129e7c>] btusb_send_frame+0x64/0xf8 [btusb]

Put those urbs in tx_anchor to avoid the leak, and also fix the error
handling.

Signed-off-by: Jeffy Chen <jeffy.chen@...k-chips.com>
---

Changes in v6:
Don't print error msg when dropping urbs, since we already log it when
failed to submit.

Changes in v5:
Fix compile warning reported by "kbuild test robot":
drivers/bluetooth/btusb.c:3288:3: warning: 'err' may be used uninitialized in this function [-Wmaybe-uninitialized]
This 'err' would be set in the send loop, and would be used in the
cleanup rest urb code outside the loop.

Changes in v4:
Drop the rest deferred urbs when error happens.

Changes in v3:
Put the deferred urbs in tx_anchor.

Changes in v2:
Call usb_free_urb instead of reusing submit_tx_urb.

 drivers/bluetooth/btusb.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 0d533b2..fa3de4f 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -3266,13 +3266,28 @@ static void play_deferred(struct btusb_data *data)
 	int err;
 
 	while ((urb = usb_get_from_anchor(&data->deferred))) {
+		usb_anchor_urb(urb, &data->tx_anchor);
+
 		err = usb_submit_urb(urb, GFP_ATOMIC);
-		if (err < 0)
+		if (err < 0) {
+			if (err != -EPERM && err != -ENODEV)
+				BT_ERR("%s urb %p submission failed (%d)",
+				       data->hdev->name, urb, -err);
+			kfree(urb->setup_packet);
+			usb_unanchor_urb(urb);
+			usb_free_urb(urb);
 			break;
+		}
 
 		data->tx_in_flight++;
+		usb_free_urb(urb);
+	}
+
+	/* Cleanup the rest deferred urbs. */
+	while ((urb = usb_get_from_anchor(&data->deferred))) {
+		kfree(urb->setup_packet);
+		usb_free_urb(urb);
 	}
-	usb_scuttle_anchored_urbs(&data->deferred);
 }
 
 static int btusb_resume(struct usb_interface *intf)
-- 
2.1.4