linux-kernel - [PATCH 4.9 05/23] usb: xhci: Handle error condition in xhci_stop

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Date:   Tue, 31 Oct 2017 10:55:29 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Mayank Rana <mrana@...eaurora.org>,
        Jack Pham <jackp@...eaurora.org>,
        Mathias Nyman <mathias.nyman@...ux.intel.com>
Subject: [PATCH 4.9 05/23] usb: xhci: Handle error condition in xhci_stop_device()

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mayank Rana <mrana@...eaurora.org>

commit b3207c65dfafae27e7c492cb9188c0dc0eeaf3fd upstream.

xhci_stop_device() calls xhci_queue_stop_endpoint() multiple times
without checking the return value. xhci_queue_stop_endpoint() can
return error if the HC is already halted or unable to queue commands.
This can cause a deadlock condition as xhci_stop_device() would
end up waiting indefinitely for a completion for the command that
didn't get queued. Fix this by checking the return value and bailing
out of xhci_stop_device() in case of error. This patch happens to fix
potential memory leaks of the allocated command structures as well.

Fixes: c311e391a7ef ("xhci: rework command timeout and cancellation,")
Signed-off-by: Mayank Rana <mrana@...eaurora.org>
Signed-off-by: Jack Pham <jackp@...eaurora.org>
Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>


---
 drivers/usb/host/xhci-hub.c |   22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -412,15 +412,25 @@ static int xhci_stop_device(struct xhci_
 						     GFP_NOWAIT);
 			if (!command) {
 				spin_unlock_irqrestore(&xhci->lock, flags);
-				xhci_free_command(xhci, cmd);
-				return -ENOMEM;
+				ret = -ENOMEM;
+				goto cmd_cleanup;
+			}
 
+			ret = xhci_queue_stop_endpoint(xhci, command, slot_id,
+						       i, suspend);
+			if (ret) {
+				spin_unlock_irqrestore(&xhci->lock, flags);
+				xhci_free_command(xhci, command);
+				goto cmd_cleanup;
 			}
-			xhci_queue_stop_endpoint(xhci, command, slot_id, i,
-						 suspend);
 		}
 	}
-	xhci_queue_stop_endpoint(xhci, cmd, slot_id, 0, suspend);
+	ret = xhci_queue_stop_endpoint(xhci, cmd, slot_id, 0, suspend);
+	if (ret) {
+		spin_unlock_irqrestore(&xhci->lock, flags);
+		goto cmd_cleanup;
+	}
+
 	xhci_ring_cmd_db(xhci);
 	spin_unlock_irqrestore(&xhci->lock, flags);
 
@@ -431,6 +441,8 @@ static int xhci_stop_device(struct xhci_
 		xhci_warn(xhci, "Timeout while waiting for stop endpoint command\n");
 		ret = -ETIME;
 	}
+
+cmd_cleanup:
 	xhci_free_command(xhci, cmd);
 	return ret;
 }