[PATCH] USB: usbfs: Don't leak uninitialized data

This patch fixes an information leak in the usbfs snoop facility:
uninitialized data from __get_free_page can be returned to userspace and
written to the system log.  It also improves the snoop output by printing
the wLength value.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 787c27a..f86bf14 100644 (file)
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -569,8 +569,11 @@ static int proc_control(struct dev_state *ps, void __user *arg)
                        free_page((unsigned long)tbuf);
                        return -EINVAL;
                }
-               snoop(&dev->dev, "control read: bRequest=%02x bRrequestType=%02x wValue=%04x wIndex=%04x\n", 
-                       ctrl.bRequest, ctrl.bRequestType, ctrl.wValue, ctrl.wIndex);
+               snoop(&dev->dev, "control read: bRequest=%02x "
+                               "bRrequestType=%02x wValue=%04x "
+                               "wIndex=%04x wLength=%04x\n",
+                       ctrl.bRequest, ctrl.bRequestType, ctrl.wValue,
+                               ctrl.wIndex, ctrl.wLength);
 
                usb_unlock_device(dev);
                i = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), ctrl.bRequest, ctrl.bRequestType,
@@ -579,11 +582,11 @@ static int proc_control(struct dev_state *ps, void __user *arg)
                if ((i > 0) && ctrl.wLength) {
                        if (usbfs_snoop) {
                                dev_info(&dev->dev, "control read: data ");
-                               for (j = 0; j < ctrl.wLength; ++j)
+                               for (j = 0; j < i; ++j)
                                        printk ("%02x ", (unsigned char)(tbuf)[j]);
                                printk("\n");
                        }
-                       if (copy_to_user(ctrl.data, tbuf, ctrl.wLength)) {
+                       if (copy_to_user(ctrl.data, tbuf, i)) {
                                free_page((unsigned long)tbuf);
                                return -EFAULT;
                        }
@@ -595,8 +598,11 @@ static int proc_control(struct dev_state *ps, void __user *arg)
                                return -EFAULT;
                        }
                }
-               snoop(&dev->dev, "control write: bRequest=%02x bRrequestType=%02x wValue=%04x wIndex=%04x\n", 
-                       ctrl.bRequest, ctrl.bRequestType, ctrl.wValue, ctrl.wIndex);
+               snoop(&dev->dev, "control write: bRequest=%02x "
+                               "bRrequestType=%02x wValue=%04x "
+                               "wIndex=%04x wLength=%04x\n",
+                       ctrl.bRequest, ctrl.bRequestType, ctrl.wValue,
+                               ctrl.wIndex, ctrl.wLength);
                if (usbfs_snoop) {
                        dev_info(&dev->dev, "control write: data: ");
                        for (j = 0; j < ctrl.wLength; ++j)