linux-kernel - [PATCH 3.16 073/366] usb: musb: gadget: misplaced out of bounds check

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Message-ID: <lsq.1539530741.364892287@decadent.org.uk>
Date:   Sun, 14 Oct 2018 16:25:41 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Heinrich Schuchardt" <xypron.glpk@....de>,
        "Bin Liu" <b-liu@...com>
Subject: [PATCH 3.16 073/366] usb: musb: gadget: misplaced out of bounds check

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

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

From: Heinrich Schuchardt <xypron.glpk@....de>

commit af6f8529098aeb0e56a68671b450cf74e7a64fcd upstream.

musb->endpoints[] has array size MUSB_C_NUM_EPS.
We must check array bounds before accessing the array and not afterwards.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@....de>
Signed-off-by: Bin Liu <b-liu@...com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/usb/musb/musb_gadget_ep0.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

--- a/drivers/usb/musb/musb_gadget_ep0.c
+++ b/drivers/usb/musb/musb_gadget_ep0.c
@@ -114,15 +114,19 @@ static int service_tx_status_request(
 		}
 
 		is_in = epnum & USB_DIR_IN;
-		if (is_in) {
-			epnum &= 0x0f;
+		epnum &= 0x0f;
+		if (epnum >= MUSB_C_NUM_EPS) {
+			handled = -EINVAL;
+			break;
+		}
+
+		if (is_in)
 			ep = &musb->endpoints[epnum].ep_in;
-		} else {
+		else
 			ep = &musb->endpoints[epnum].ep_out;
-		}
 		regs = musb->endpoints[epnum].regs;
 
-		if (epnum >= MUSB_C_NUM_EPS || !ep->desc) {
+		if (!ep->desc) {
 			handled = -EINVAL;
 			break;
 		}