usb: composite: fix possible alignment issues

Since upgrading to gcc9, warnings are issued:
"taking address of packed member of ‘...’ may result in an unaligned
pointer value"

Fix this by converting two functions to use unaligned access since packed
structures may be on an unaligned address, depending on USB hardware.

Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 618a7d5016ee42416edffe01e066793ebbb64a4b..c98a444245c28b6d77495e5fabfce07f481160c1 100644 (file)
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -12,8 +12,16 @@
 
 #define USB_BUFSIZ     4096
 
+/* Helper type for accessing packed u16 pointers */
+typedef struct { __le16 val; } __packed __le16_packed;
+
 static struct usb_composite_driver *composite;
 
+static inline void le16_add_cpu_packed(__le16_packed *var, u16 val)
+{
+       var->val = cpu_to_le16(le16_to_cpu(var->val) + val);
+}
+
 /**
  * usb_add_function() - add a function to a configuration
  * @config: the configuration
@@ -480,20 +488,21 @@ done:
  * the host side.
  */
 
-static void collect_langs(struct usb_gadget_strings **sp, __le16 *buf)
+static void collect_langs(struct usb_gadget_strings **sp, void *buf)
 {
        const struct usb_gadget_strings *s;
        u16                             language;
-       __le16                          *tmp;
+       __le16_packed                   *tmp;
+       __le16_packed                   *end = (buf + 252);
 
        while (*sp) {
                s = *sp;
                language = cpu_to_le16(s->language);
-               for (tmp = buf; *tmp && tmp < &buf[126]; tmp++) {
-                       if (*tmp == language)
+               for (tmp = buf; tmp->val && tmp < end; tmp++) {
+                       if (tmp->val == language)
                                goto repeat;
                }
-               *tmp++ = language;
+               tmp->val = language;
 repeat:
                sp++;
        }
@@ -705,7 +714,8 @@ static int bos_desc(struct usb_composite_dev *cdev)
         */
        usb_ext = cdev->req->buf + le16_to_cpu(bos->wTotalLength);
        bos->bNumDeviceCaps++;
-       le16_add_cpu(&bos->wTotalLength, USB_DT_USB_EXT_CAP_SIZE);
+       le16_add_cpu_packed((__le16_packed *)&bos->wTotalLength,
+                           USB_DT_USB_EXT_CAP_SIZE);
        usb_ext->bLength = USB_DT_USB_EXT_CAP_SIZE;
        usb_ext->bDescriptorType = USB_DT_DEVICE_CAPABILITY;
        usb_ext->bDevCapabilityType = USB_CAP_TYPE_EXT;
@@ -721,7 +731,8 @@ static int bos_desc(struct usb_composite_dev *cdev)
 
                ss_cap = cdev->req->buf + le16_to_cpu(bos->wTotalLength);
                bos->bNumDeviceCaps++;
-               le16_add_cpu(&bos->wTotalLength, USB_DT_USB_SS_CAP_SIZE);
+               le16_add_cpu_packed((__le16_packed *)&bos->wTotalLength,
+                                   USB_DT_USB_SS_CAP_SIZE);
                ss_cap->bLength = USB_DT_USB_SS_CAP_SIZE;
                ss_cap->bDescriptorType = USB_DT_DEVICE_CAPABILITY;
                ss_cap->bDevCapabilityType = USB_SS_CAP_TYPE;