USB: wusb: don't use the stack to read security descriptor

An urb's transfer buffer must be kmalloc'd memory and not point to the
stack or a DMA API warning results.

Signed-off-by: David Vrabel <david.vrabel@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 19 insertions, 22 deletions

diff --git a/drivers/usb/wusbcore/security.c b/drivers/usb/wusbcore/security.c
index b2f149fedcc..4516c36436e 100644
--- a/drivers/usb/wusbcore/security.c
+++ b/drivers/usb/wusbcore/security.c
@@ -200,35 +200,40 @@ int wusb_dev_sec_add(struct wusbhc *wusbhc,
 {
         int result, bytes, secd_size;
         struct device *dev = &usb_dev->dev;
-        struct usb_security_descriptor secd;
+        struct usb_security_descriptor *secd;
         const struct usb_encryption_descriptor *etd, *ccm1_etd = NULL;
-        void *secd_buf;
         const void *itr, *top;
         char buf[64];
 
+        secd = kmalloc(sizeof(struct usb_security_descriptor), GFP_KERNEL);
+        if (secd == NULL) {
+                result = -ENOMEM;
+                goto out;
+        }
+
         result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
-                                    0, &secd, sizeof(secd));
+                                    0, secd, sizeof(struct usb_security_descriptor));
         if (result < sizeof(secd)) {
                 dev_err(dev, "Can't read security descriptor or "
                         "not enough data: %d\n", result);
-                goto error_secd;
+                goto out;
         }
-        secd_size = le16_to_cpu(secd.wTotalLength);
-        secd_buf = kmalloc(secd_size, GFP_KERNEL);
-        if (secd_buf == NULL) {
+        secd_size = le16_to_cpu(secd->wTotalLength);
+        secd = krealloc(secd, secd_size, GFP_KERNEL);
+        if (secd == NULL) {
                 dev_err(dev, "Can't allocate space for security descriptors\n");
-                goto error_secd_alloc;
+                goto out;
         }
         result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
-                                    0, secd_buf, secd_size);
+                                    0, secd, secd_size);
         if (result < secd_size) {
                 dev_err(dev, "Can't read security descriptor or "
                         "not enough data: %d\n", result);
-                goto error_secd_all;
+                goto out;
         }
         bytes = 0;
-        itr = secd_buf + sizeof(secd);
-        top = secd_buf + result;
+        itr = &secd[1];
+        top = (void *)secd + result;
         while (itr < top) {
                 etd = itr;
                 if (top - itr < sizeof(*etd)) {
@@ -259,24 +264,16 @@ int wusb_dev_sec_add(struct wusbhc *wusbhc,
                 dev_err(dev, "WUSB device doesn't support CCM1 encryption, "
                         "can't use!\n");
                 result = -EINVAL;
-                goto error_no_ccm1;
+                goto out;
         }
         wusb_dev->ccm1_etd = *ccm1_etd;
         dev_dbg(dev, "supported encryption: %s; using %s (0x%02x/%02x)\n",
                 buf, wusb_et_name(ccm1_etd->bEncryptionType),
                 ccm1_etd->bEncryptionValue, ccm1_etd->bAuthKeyIndex);
         result = 0;
-        kfree(secd_buf);
 out:
+        kfree(secd);
         return result;
-
-
-error_no_ccm1:
-error_secd_all:
-        kfree(secd_buf);
-error_secd_alloc:
-error_secd:
-        goto out;
 }
 
 void wusb_dev_sec_rm(struct wusb_dev *wusb_dev)