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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, "Secunia Research" <vuln@secunia.com>,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
        "Shuah Khan" <shuahkh@osg.samsung.com>
Date:   Sun, 11 Feb 2018 04:20:06 +0000
Message-ID: <lsq.1518322806.245935806@decadent.org.uk>
Subject: [PATCH 3.2 73/79] usbip: fix stub_rx: get_pipe() to validate
 endpoint number
In-Reply-To: <lsq.1518322802.943358572@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

3.2.99-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Shuah Khan <shuahkh@osg.samsung.com>

commit 635f545a7e8be7596b9b2b6a43cab6bbd5a88e43 upstream.

get_pipe() routine doesn't validate the input endpoint number
and uses to reference ep_in and ep_out arrays. Invalid endpoint
number can trigger BUG(). Range check the epnum and returning
error instead of calling BUG().

Change caller stub_recv_cmd_submit() to handle the get_pipe()
error return.

Reported-by: Secunia Research <vuln@secunia.com>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/staging/usbip/stub_rx.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

--- a/drivers/staging/usbip/stub_rx.c
+++ b/drivers/staging/usbip/stub_rx.c
@@ -356,15 +356,15 @@ static int get_pipe(struct stub_device *
 	struct usb_host_endpoint *ep;
 	struct usb_endpoint_descriptor *epd = NULL;
 
+	if (epnum < 0 || epnum > 15)
+		goto err_ret;
+
 	if (dir == USBIP_DIR_IN)
 		ep = udev->ep_in[epnum & 0x7f];
 	else
 		ep = udev->ep_out[epnum & 0x7f];
-	if (!ep) {
-		dev_err(&sdev->interface->dev, "no such endpoint?, %d\n",
-			epnum);
-		BUG();
-	}
+	if (!ep)
+		goto err_ret;
 
 	epd = &ep->desc;
 	if (usb_endpoint_xfer_control(epd)) {
@@ -395,9 +395,10 @@ static int get_pipe(struct stub_device *
 			return usb_rcvisocpipe(udev, epnum);
 	}
 
+err_ret:
 	/* NOT REACHED */
-	dev_err(&sdev->interface->dev, "get pipe, epnum %d\n", epnum);
-	return 0;
+	dev_err(&sdev->interface->dev, "get pipe() invalid epnum %d\n", epnum);
+	return -1;
 }
 
 static void masking_bogus_flags(struct urb *urb)
@@ -463,6 +464,9 @@ static void stub_recv_cmd_submit(struct
 	struct usb_device *udev = sdev->udev;
 	int pipe = get_pipe(sdev, pdu->base.ep, pdu->base.direction);
 
+	if (pipe == -1)
+		return;
+
 	priv = stub_priv_alloc(sdev, pdu);
 	if (!priv)
 		return;