[PATCH] usb/mcs7830: Don't use buffers from stack for USB transfers

["Christian Eggers" <ceggers@gmx.de>]

From: Christian Eggers <christian.eggers@kathrein.de>

mcs7830_set_reg() and mcs7830_get_reg() are called with buffers
from stack which must not be used directly for USB transfers.
This causes corruption of the stack particulary on non x86
architectures because DMA may be used for these transfers.

Signed-off-by: Christian Eggers <christian.eggers@kathrein.de>
---

This is my first patch submission for Linux. I hope everything is fine.

diff -uprN linux-2.6.28.1.orig/drivers/net/usb/mcs7830.c linux-2.6.28.1/drivers/net/usb/mcs7830.c
--- linux-2.6.28.1.orig/drivers/net/usb/mcs7830.c       2009-01-18 19:45:37.000000000 +0100
+++ linux-2.6.28.1/drivers/net/usb/mcs7830.c    2009-01-20 20:53:59.000000000 +0100
@@ -94,10 +94,18 @@ static int mcs7830_get_reg(struct usbnet
 {
        struct usb_device *xdev = dev->udev;
        int ret;
+       void *buffer;
+
+       buffer = kmalloc(size, GFP_NOIO);
+       if (buffer == NULL)
+               return -ENOMEM;

        ret = usb_control_msg(xdev, usb_rcvctrlpipe(xdev, 0), MCS7830_RD_BREQ,
-                             MCS7830_RD_BMREQ, 0x0000, index, data,
+                             MCS7830_RD_BMREQ, 0x0000, index, buffer,
                              size, MCS7830_CTRL_TIMEOUT);
+       memcpy(data, buffer, size);
+       kfree(buffer);
+
        return ret;
 }

@@ -105,10 +113,18 @@ static int mcs7830_set_reg(struct usbnet
 {
        struct usb_device *xdev = dev->udev;
        int ret;
+       void *buffer;
+
+       buffer = kmalloc(size, GFP_NOIO);
+       if (buffer == NULL)
+               return -ENOMEM;
+
+       memcpy(buffer, data, size);

        ret = usb_control_msg(xdev, usb_sndctrlpipe(xdev, 0), MCS7830_WR_BREQ,
-                             MCS7830_WR_BMREQ, 0x0000, index, data,
+                             MCS7830_WR_BMREQ, 0x0000, index, buffer,
                              size, MCS7830_CTRL_TIMEOUT);
+       kfree(buffer);
        return ret;
 }