usb: xhci: Fix potential memory leak in xhci_disable_slot()

xhci_disable_slot() allows the invoker to pass a command pointer
as paramenter. Otherwise, it will allocate one. This will cause
memory leak when a command structure was allocated inside of this
function while queuing command trb fails. Another problem comes up
when the invoker passed a command pointer, but xhci_disable_slot()
frees it when it detects a dead host.

This patch fixes these two problems by removing the command parameter
from xhci_disable_slot().

Fixes: f9e609b82479 ("usb: xhci: Add helper function xhci_disable_slot().")
Cc: Guoqing Zhang <guoqing.zhang@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-hub.c

@@ -615,7 +615,7 @@ static int xhci_enter_test_mode(struct xhci_hcd *xhci,
 		if (!xhci->devs[i])
 			continue;
 
-		retval = xhci_disable_slot(xhci, NULL, i);
+		retval = xhci_disable_slot(xhci, i);
 		if (retval)
 			xhci_err(xhci, "Failed to disable slot %d, %d. Enter test mode anyway\n",
 				 i, retval);

drivers/usb/host/xhci.c

@@ -3531,14 +3531,9 @@ static void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
 	struct xhci_virt_device *virt_dev;
 	struct xhci_slot_ctx *slot_ctx;
 	int i, ret;
-	struct xhci_command *command;
 
 	xhci_debugfs_remove_slot(xhci, udev->slot_id);
 
-	command = xhci_alloc_command(xhci, false, false, GFP_KERNEL);
-	if (!command)
-		return;
-
 #ifndef CONFIG_USB_DEFAULT_PERSIST
 	/*
 	 * We called pm_runtime_get_noresume when the device was attached.
@@ -3553,10 +3548,8 @@ static void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
 	/* If the host is halted due to driver unload, we still need to free the
 	 * device.
 	 */
-	if (ret <= 0 && ret != -ENODEV) {
-		kfree(command);
+	if (ret <= 0 && ret != -ENODEV)
 		return;
-	}
 
 	virt_dev = xhci->devs[udev->slot_id];
 	slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->out_ctx);
@@ -3568,22 +3561,21 @@ static void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
 		del_timer_sync(&virt_dev->eps[i].stop_cmd_timer);
 	}
 
-	xhci_disable_slot(xhci, command, udev->slot_id);
+	xhci_disable_slot(xhci, udev->slot_id);
 	/*
 	 * Event command completion handler will free any data structures
 	 * associated with the slot.  XXX Can free sleep?
 	 */
 }
 
-int xhci_disable_slot(struct xhci_hcd *xhci, struct xhci_command *command,
-			u32 slot_id)
+int xhci_disable_slot(struct xhci_hcd *xhci, u32 slot_id)
 {
+	struct xhci_command *command;
 	unsigned long flags;
 	u32 state;
 	int ret = 0;
 
-	if (!command)
-		command = xhci_alloc_command(xhci, false, false, GFP_KERNEL);
+	command = xhci_alloc_command(xhci, false, false, GFP_KERNEL);
 	if (!command)
 		return -ENOMEM;
 
@@ -3602,7 +3594,7 @@ int xhci_disable_slot(struct xhci_hcd *xhci, struct xhci_command *command,
 				slot_id);
 	if (ret) {
 		spin_unlock_irqrestore(&xhci->lock, flags);
-		xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");
+		kfree(command);
 		return ret;
 	}
 	xhci_ring_cmd_db(xhci);
@@ -3677,6 +3669,8 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
 		return 0;
 	}
 
+	xhci_free_command(xhci, command);
+
 	if ((xhci->quirks & XHCI_EP_LIMIT_QUIRK)) {
 		spin_lock_irqsave(&xhci->lock, flags);
 		ret = xhci_reserve_host_control_ep_resources(xhci);
@@ -3714,18 +3708,12 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
 		pm_runtime_get_noresume(hcd->self.controller);
 #endif
 
-
-	xhci_free_command(xhci, command);
 	/* Is this a LS or FS device under a HS hub? */
 	/* Hub or peripherial? */
 	return 1;
 
 disable_slot:
-	/* Disable slot, if we can do it without mem alloc */
-	kfree(command->completion);
-	command->completion = NULL;
-	command->status = 0;
-	return xhci_disable_slot(xhci, command, udev->slot_id);
+	return xhci_disable_slot(xhci, udev->slot_id);
 }
 
 /*

drivers/usb/host/xhci.h

@@ -2019,8 +2019,7 @@ int xhci_run(struct usb_hcd *hcd);
 int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks);
 void xhci_init_driver(struct hc_driver *drv,
 		      const struct xhci_driver_overrides *over);
-int xhci_disable_slot(struct xhci_hcd *xhci,
-			struct xhci_command *command, u32 slot_id);
+int xhci_disable_slot(struct xhci_hcd *xhci, u32 slot_id);
 
 int xhci_suspend(struct xhci_hcd *xhci, bool do_wakeup);
 int xhci_resume(struct xhci_hcd *xhci, bool hibernated);