[ 3.8.y.z extended stable ] Patch "USB: mos7840: fix DMA to stack" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    USB: mos7840: fix DMA to stack

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.3.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 5236c026d8169955901df32aa3ef151a49f27b15 Mon Sep 17 00:00:00 2001
From: Johan Hovold <jhovold at gmail.com>
Date: Mon, 27 May 2013 14:44:40 +0200
Subject: USB: mos7840: fix DMA to stack

commit 15ee89c3347fbf58a4361011eda5ac2731e45126 upstream.

Fix regression introduced by commit 0eafe4de1a ("USB: serial: mos7840:
add support for MCS7810 devices") which used stack-allocated buffers for
control messages.

Signed-off-by: Johan Hovold <jhovold at gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/usb/serial/mos7840.c | 35 +++++++++++++++++++++++++++--------
 1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/serial/mos7840.c b/drivers/usb/serial/mos7840.c
index 3b909e0..54f23f0 100644
--- a/drivers/usb/serial/mos7840.c
+++ b/drivers/usb/serial/mos7840.c
@@ -2259,13 +2259,21 @@ static int mos7840_ioctl(struct tty_struct *tty,
 static int mos7810_check(struct usb_serial *serial)
 {
 	int i, pass_count = 0;
+	u8 *buf;
 	__u16 data = 0, mcr_data = 0;
 	__u16 test_pattern = 0x55AA;
+	int res;
+
+	buf = kmalloc(VENDOR_READ_LENGTH, GFP_KERNEL);
+	if (!buf)
+		return 0;	/* failed to identify 7810 */

 	/* Store MCR setting */
-	usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
+	res = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
 		MCS_RDREQ, MCS_RD_RTYPE, 0x0300, MODEM_CONTROL_REGISTER,
-		&mcr_data, VENDOR_READ_LENGTH, MOS_WDR_TIMEOUT);
+		buf, VENDOR_READ_LENGTH, MOS_WDR_TIMEOUT);
+	if (res == VENDOR_READ_LENGTH)
+		mcr_data = *buf;

 	for (i = 0; i < 16; i++) {
 		/* Send the 1-bit test pattern out to MCS7810 test pin */
@@ -2275,9 +2283,12 @@ static int mos7810_check(struct usb_serial *serial)
 			MODEM_CONTROL_REGISTER, NULL, 0, MOS_WDR_TIMEOUT);

 		/* Read the test pattern back */
-		usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
-			MCS_RDREQ, MCS_RD_RTYPE, 0, GPIO_REGISTER, &data,
-			VENDOR_READ_LENGTH, MOS_WDR_TIMEOUT);
+		res = usb_control_msg(serial->dev,
+				usb_rcvctrlpipe(serial->dev, 0), MCS_RDREQ,
+				MCS_RD_RTYPE, 0, GPIO_REGISTER, buf,
+				VENDOR_READ_LENGTH, MOS_WDR_TIMEOUT);
+		if (res == VENDOR_READ_LENGTH)
+			data = *buf;

 		/* If this is a MCS7810 device, both test patterns must match */
 		if (((test_pattern >> i) ^ (~data >> 1)) & 0x0001)
@@ -2291,6 +2302,8 @@ static int mos7810_check(struct usb_serial *serial)
 		MCS_WR_RTYPE, 0x0300 | mcr_data, MODEM_CONTROL_REGISTER, NULL,
 		0, MOS_WDR_TIMEOUT);

+	kfree(buf);
+
 	if (pass_count == 16)
 		return 1;

@@ -2300,11 +2313,17 @@ static int mos7810_check(struct usb_serial *serial)
 static int mos7840_calc_num_ports(struct usb_serial *serial)
 {
 	__u16 data = 0x00;
+	u8 *buf;
 	int mos7840_num_ports;

-	usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
-		MCS_RDREQ, MCS_RD_RTYPE, 0, GPIO_REGISTER, &data,
-		VENDOR_READ_LENGTH, MOS_WDR_TIMEOUT);
+	buf = kzalloc(VENDOR_READ_LENGTH, GFP_KERNEL);
+	if (buf) {
+		usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
+			MCS_RDREQ, MCS_RD_RTYPE, 0, GPIO_REGISTER, buf,
+			VENDOR_READ_LENGTH, MOS_WDR_TIMEOUT);
+		data = *buf;
+		kfree(buf);
+	}

 	if (serial->dev->descriptor.idProduct == MOSCHIP_DEVICE_ID_7810 ||
 		serial->dev->descriptor.idProduct == MOSCHIP_DEVICE_ID_7820) {
--
1.8.1.2