[PATCH 4.9 14/25] USB: replace hardcode maximum usb string length by definition

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Macpaul Lin <macpaul.lin@mediatek.com>

commit 81c7462883b0cc0a4eeef0687f80ad5b5baee5f6 upstream.

Replace hardcoded maximum USB string length (126 bytes) by definition
"USB_MAX_STRING_LEN".

Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/1592471618-29428-1-git-send-email-macpaul.lin@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/gadget/composite.c |    4 ++--
 drivers/usb/gadget/configfs.c  |    2 +-
 drivers/usb/gadget/usbstring.c |    4 ++--
 include/uapi/linux/usb/ch9.h   |    3 +++
 4 files changed, 8 insertions(+), 5 deletions(-)

--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -1076,7 +1076,7 @@ static void collect_langs(struct usb_gad
 	while (*sp) {
 		s = *sp;
 		language = cpu_to_le16(s->language);
-		for (tmp = buf; *tmp && tmp < &buf[126]; tmp++) {
+		for (tmp = buf; *tmp && tmp < &buf[USB_MAX_STRING_LEN]; tmp++) {
 			if (*tmp == language)
 				goto repeat;
 		}
@@ -1151,7 +1151,7 @@ static int get_string(struct usb_composi
 			collect_langs(sp, s->wData);
 		}
 
-		for (len = 0; len <= 126 && s->wData[len]; len++)
+		for (len = 0; len <= USB_MAX_STRING_LEN && s->wData[len]; len++)
 			continue;
 		if (!len)
 			return -EINVAL;
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c
@@ -114,7 +114,7 @@ static int usb_string_copy(const char *s
 	char *str;
 	char *copy = *s_copy;
 	ret = strlen(s);
-	if (ret > 126)
+	if (ret > USB_MAX_STRING_LEN)
 		return -EOVERFLOW;
 
 	str = kstrdup(s, GFP_KERNEL);
--- a/drivers/usb/gadget/usbstring.c
+++ b/drivers/usb/gadget/usbstring.c
@@ -59,9 +59,9 @@ usb_gadget_get_string (struct usb_gadget
 		return -EINVAL;
 
 	/* string descriptors have length, tag, then UTF16-LE text */
-	len = min ((size_t) 126, strlen (s->s));
+	len = min((size_t)USB_MAX_STRING_LEN, strlen(s->s));
 	len = utf8s_to_utf16s(s->s, len, UTF16_LITTLE_ENDIAN,
-			(wchar_t *) &buf[2], 126);
+			(wchar_t *) &buf[2], USB_MAX_STRING_LEN);
 	if (len < 0)
 		return -EINVAL;
 	buf [0] = (len + 1) * 2;
--- a/include/uapi/linux/usb/ch9.h
+++ b/include/uapi/linux/usb/ch9.h
@@ -358,6 +358,9 @@ struct usb_config_descriptor {
 
 /*-------------------------------------------------------------------------*/
 
+/* USB String descriptors can contain at most 126 characters. */
+#define USB_MAX_STRING_LEN	126
+
 /* USB_DT_STRING: String descriptor */
 struct usb_string_descriptor {
 	__u8  bLength;