hso: Fix stack corruption on some architectures

As Sergei Shtylyov explained in the #mipslinux IRC channel:
[Mon 2013-08-19 12:28:21 PM PDT] <headless> guys, are you sure it's not "DMA off stack" case?
[Mon 2013-08-19 12:28:35 PM PDT] <headless> it's a known stack corruptor on non-coherent arches
[Mon 2013-08-19 12:31:48 PM PDT] <DonkeyHotei> headless: for usb/ehci?
[Mon 2013-08-19 12:34:11 PM PDT] <DonkeyHotei> headless: explain
[Mon 2013-08-19 12:35:38 PM PDT] <headless> usb_control_msg() (or other such func) should not use buffer on stack. DMA from/to stack is prohibited
[Mon 2013-08-19 12:35:58 PM PDT] <headless> and EHCI uses DMA on control xfers (as well as all the others)

Signed-off-by: Daniel Gimpelevich <daniel@gimpelevich.san-francisco.ca.us>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index 5fb36ed23c1f139efa68bb2a49ff84f6fefa9577..86292e6aaf4955c4412ead6579f74e6848bcd089 100644 (file)
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -2816,13 +2816,16 @@ exit:
 static int hso_get_config_data(struct usb_interface *interface)
 {
        struct usb_device *usbdev = interface_to_usbdev(interface);
-       u8 config_data[17];
+       u8 *config_data = kmalloc(17, GFP_KERNEL);
        u32 if_num = interface->altsetting->desc.bInterfaceNumber;
        s32 result;
 
+       if (!config_data)
+               return -ENOMEM;
        if (usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0),
                            0x86, 0xC0, 0, 0, config_data, 17,
                            USB_CTRL_SET_TIMEOUT) != 0x11) {
+               kfree(config_data);
                return -EIO;
        }
 
@@ -2873,6 +2876,7 @@ static int hso_get_config_data(struct usb_interface *interface)
        if (config_data[16] & 0x1)
                result |= HSO_INFO_CRC_BUG;
 
+       kfree(config_data);
        return result;
 }