[PATCH] usb: replace hardcoded maximum usb string length by definition

[PATCH] usb: replace hardcoded maximum usb string length by definition

[Macpaul Lin]

Replace hardcoded maximum usb string length (126 bytes) by definition
"MAX_USB_STRING_LEN".

Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
---
 drivers/usb/gadget/composite.c |    4 ++--
 drivers/usb/gadget/configfs.c  |    3 ++-
 drivers/usb/gadget/usbstring.c |    5 +++--
 include/linux/usb.h            |    2 ++
 4 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index cb4950c..d0de016 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -1041,7 +1041,7 @@ static void collect_langs(struct usb_gadget_strings **sp, __le16 *buf)
 	while (*sp) {
 		s = *sp;
 		language = cpu_to_le16(s->language);
-		for (tmp = buf; *tmp && tmp < &buf[126]; tmp++) {
+		for (tmp = buf; *tmp && tmp < &buf[MAX_USB_STRING_LEN]; tmp++) {
 			if (*tmp == language)
 				goto repeat;
 		}
@@ -1116,7 +1116,7 @@ static int get_string(struct usb_composite_dev *cdev,
 			collect_langs(sp, s->wData);
 		}
 
-		for (len = 0; len <= 126 && s->wData[len]; len++)
+		for (len = 0; len <= MAX_USB_STRING_LEN && s->wData[len]; len++)
 			continue;
 		if (!len)
 			return -EINVAL;
diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index 32b637e..c9d61ac 100644
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c
@@ -4,6 +4,7 @@
 #include <linux/slab.h>
 #include <linux/device.h>
 #include <linux/nls.h>
+#include <linux/usb.h>
 #include <linux/usb/composite.h>
 #include <linux/usb/gadget_configfs.h>
 #include "configfs.h"
@@ -115,7 +116,7 @@ static int usb_string_copy(const char *s, char **s_copy)
 	char *str;
 	char *copy = *s_copy;
 	ret = strlen(s);
-	if (ret > 126)
+	if (ret > MAX_USB_STRING_LEN)
 		return -EOVERFLOW;
 
 	str = kstrdup(s, GFP_KERNEL);
diff --git a/drivers/usb/gadget/usbstring.c b/drivers/usb/gadget/usbstring.c
index 7c24d1c..c125d59 100644
--- a/drivers/usb/gadget/usbstring.c
+++ b/drivers/usb/gadget/usbstring.c
@@ -11,6 +11,7 @@
 #include <linux/device.h>
 #include <linux/nls.h>
 
+#include <linux/usb.h>
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
 
@@ -55,9 +56,9 @@
 		return -EINVAL;
 
 	/* string descriptors have length, tag, then UTF16-LE text */
-	len = min ((size_t) 126, strlen (s->s));
+	len = min((size_t)MAX_USB_STRING_LEN, strlen(s->s));
 	len = utf8s_to_utf16s(s->s, len, UTF16_LITTLE_ENDIAN,
-			(wchar_t *) &buf[2], 126);
+			(wchar_t *) &buf[2], MAX_USB_STRING_LEN);
 	if (len < 0)
 		return -EINVAL;
 	buf [0] = (len + 1) * 2;
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 9f3c721..df4a9cb 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1815,6 +1815,8 @@ static inline int usb_get_ptm_status(struct usb_device *dev, void *data)
 		0, data);
 }
 
+/* USB String descriptors can contain at most 126 characters. */
+#define MAX_USB_STRING_LEN	126
 extern int usb_string(struct usb_device *dev, int index,
 	char *buf, size_t size);
 
-- 
1.7.9.5

Re: [PATCH] usb: replace hardcoded maximum usb string length by definition

[Alan Stern]

On Fri, Jun 12, 2020 at 01:32:47PM +0800, Macpaul Lin wrote:
> Replace hardcoded maximum usb string length (126 bytes) by definition
> "MAX_USB_STRING_LEN".
> 
> Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>

...

> diff --git a/include/linux/usb.h b/include/linux/usb.h
> index 9f3c721..df4a9cb 100644
> --- a/include/linux/usb.h
> +++ b/include/linux/usb.h
> @@ -1815,6 +1815,8 @@ static inline int usb_get_ptm_status(struct usb_device *dev, void *data)
>  		0, data);
>  }
>  
> +/* USB String descriptors can contain at most 126 characters. */
> +#define MAX_USB_STRING_LEN	126

This definition belongs in include/uapi/linux/usb/ch9.h (near the 
definition of struct usb_string_descriptor) because it is part of the USB 
standard rather than specific to the Linux USB stack.

Alan Stern

[PATCH v2] usb: replace hardcode maximum usb string length by definition

[Macpaul Lin]

Replace hardcode maximum usb string length (126 bytes) by definition
"MAX_USB_STRING_LEN".

Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
---
Changes for v2:
  - Add definition "MAX_USB_STRING_LEN" in ch9.h instead of in usb.h.
    Thanks for Alan's suggestion.

 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(-)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index cb4950c..d0de016 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -1041,7 +1041,7 @@ static void collect_langs(struct usb_gadget_strings **sp, __le16 *buf)
 	while (*sp) {
 		s = *sp;
 		language = cpu_to_le16(s->language);
-		for (tmp = buf; *tmp && tmp < &buf[126]; tmp++) {
+		for (tmp = buf; *tmp && tmp < &buf[MAX_USB_STRING_LEN]; tmp++) {
 			if (*tmp == language)
 				goto repeat;
 		}
@@ -1116,7 +1116,7 @@ static int get_string(struct usb_composite_dev *cdev,
 			collect_langs(sp, s->wData);
 		}
 
-		for (len = 0; len <= 126 && s->wData[len]; len++)
+		for (len = 0; len <= MAX_USB_STRING_LEN && s->wData[len]; len++)
 			continue;
 		if (!len)
 			return -EINVAL;
diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index 32b637e..70dd4ba 100644
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c
@@ -115,7 +115,7 @@ static int usb_string_copy(const char *s, char **s_copy)
 	char *str;
 	char *copy = *s_copy;
 	ret = strlen(s);
-	if (ret > 126)
+	if (ret > MAX_USB_STRING_LEN)
 		return -EOVERFLOW;
 
 	str = kstrdup(s, GFP_KERNEL);
diff --git a/drivers/usb/gadget/usbstring.c b/drivers/usb/gadget/usbstring.c
index 7c24d1c..8a8d647 100644
--- a/drivers/usb/gadget/usbstring.c
+++ b/drivers/usb/gadget/usbstring.c
@@ -55,9 +55,9 @@
 		return -EINVAL;
 
 	/* string descriptors have length, tag, then UTF16-LE text */
-	len = min((size_t) 126, strlen (s->s));
+	len = min((size_t)MAX_USB_STRING_LEN, strlen(s->s));
 	len = utf8s_to_utf16s(s->s, len, UTF16_LITTLE_ENDIAN,
-			(wchar_t *) &buf[2], 126);
+			(wchar_t *) &buf[2], MAX_USB_STRING_LEN);
 	if (len < 0)
 		return -EINVAL;
 	buf [0] = (len + 1) * 2;
diff --git a/include/uapi/linux/usb/ch9.h b/include/uapi/linux/usb/ch9.h
index 2b623f3..cc02d05 100644
--- a/include/uapi/linux/usb/ch9.h
+++ b/include/uapi/linux/usb/ch9.h
@@ -364,6 +364,9 @@ struct usb_config_descriptor {
 
 /*-------------------------------------------------------------------------*/
 
+/* USB String descriptors can contain at most 126 characters. */
+#define MAX_USB_STRING_LEN	126
+
 /* USB_DT_STRING: String descriptor */
 struct usb_string_descriptor {
 	__u8  bLength;
-- 
1.7.9.5

Re: [PATCH v2] usb: replace hardcode maximum usb string length by definition

[Alan Stern]

On Mon, Jun 15, 2020 at 02:17:35PM +0800, Macpaul Lin wrote:
> Replace hardcode maximum usb string length (126 bytes) by definition
> "MAX_USB_STRING_LEN".
> 
> Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
> ---
> Changes for v2:
>   - Add definition "MAX_USB_STRING_LEN" in ch9.h instead of in usb.h.
>     Thanks for Alan's suggestion.

Acked-by: Alan Stern <stern@rowland.harvard.edu>

Re: [PATCH v2] usb: replace hardcode maximum usb string length by definition

[Greg Kroah-Hartman]

On Mon, Jun 15, 2020 at 02:17:35PM +0800, Macpaul Lin wrote:
> Replace hardcode maximum usb string length (126 bytes) by definition
> "MAX_USB_STRING_LEN".
> 
> Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
> ---
> Changes for v2:
>   - Add definition "MAX_USB_STRING_LEN" in ch9.h instead of in usb.h.
>     Thanks for Alan's suggestion.
> 
>  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(-)

This patch fails to apply to my tree (or to 5.8-rc1).  Please rebase it
and resend.

thanks,

greg k-h

[PATCH v3] usb: replace hardcode maximum usb string length by definition

[Macpaul Lin]

Replace hardcode maximum usb string length (126 bytes) by definition
"MAX_USB_STRING_LEN".

Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
---
Changes for v2:
  - Add definition "MAX_USB_STRING_LEN" in ch9.h instead of in usb.h.
    Thanks for Alan's suggestion.
Changes for v3:
  - Rebase to 5.8-rc1 and resolve conflict.

 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(-)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index cb4950c..d0de016 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -1041,7 +1041,7 @@ static void collect_langs(struct usb_gadget_strings **sp, __le16 *buf)
 	while (*sp) {
 		s = *sp;
 		language = cpu_to_le16(s->language);
-		for (tmp = buf; *tmp && tmp < &buf[126]; tmp++) {
+		for (tmp = buf; *tmp && tmp < &buf[MAX_USB_STRING_LEN]; tmp++) {
 			if (*tmp == language)
 				goto repeat;
 		}
@@ -1116,7 +1116,7 @@ static int get_string(struct usb_composite_dev *cdev,
 			collect_langs(sp, s->wData);
 		}
 
-		for (len = 0; len <= 126 && s->wData[len]; len++)
+		for (len = 0; len <= MAX_USB_STRING_LEN && s->wData[len]; len++)
 			continue;
 		if (!len)
 			return -EINVAL;
diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index 32b637e..70dd4ba 100644
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c
@@ -115,7 +115,7 @@ static int usb_string_copy(const char *s, char **s_copy)
 	char *str;
 	char *copy = *s_copy;
 	ret = strlen(s);
-	if (ret > 126)
+	if (ret > MAX_USB_STRING_LEN)
 		return -EOVERFLOW;
 
 	str = kstrdup(s, GFP_KERNEL);
diff --git a/drivers/usb/gadget/usbstring.c b/drivers/usb/gadget/usbstring.c
index 7c24d1c..8a8d647 100644
--- a/drivers/usb/gadget/usbstring.c
+++ b/drivers/usb/gadget/usbstring.c
@@ -55,9 +55,9 @@
 		return -EINVAL;
 
 	/* string descriptors have length, tag, then UTF16-LE text */
-	len = min ((size_t) 126, strlen (s->s));
+	len = min((size_t)MAX_USB_STRING_LEN, strlen(s->s));
 	len = utf8s_to_utf16s(s->s, len, UTF16_LITTLE_ENDIAN,
-			(wchar_t *) &buf[2], 126);
+			(wchar_t *) &buf[2], MAX_USB_STRING_LEN);
 	if (len < 0)
 		return -EINVAL;
 	buf [0] = (len + 1) * 2;
diff --git a/include/uapi/linux/usb/ch9.h b/include/uapi/linux/usb/ch9.h
index 2b623f3..cc02d05 100644
--- a/include/uapi/linux/usb/ch9.h
+++ b/include/uapi/linux/usb/ch9.h
@@ -364,6 +364,9 @@ struct usb_config_descriptor {
 
 /*-------------------------------------------------------------------------*/
 
+/* USB String descriptors can contain at most 126 characters. */
+#define MAX_USB_STRING_LEN	126
+
 /* USB_DT_STRING: String descriptor */
 struct usb_string_descriptor {
 	__u8  bLength;
-- 
1.7.9.5

Re: [PATCH v3] usb: replace hardcode maximum usb string length by definition

[Greg Kroah-Hartman]

On Thu, Jun 18, 2020 at 05:13:38PM +0800, Macpaul Lin wrote:
> Replace hardcode maximum usb string length (126 bytes) by definition
> "MAX_USB_STRING_LEN".
> 
> Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
> Acked-by: Alan Stern <stern@rowland.harvard.edu>
> ---
> Changes for v2:
>   - Add definition "MAX_USB_STRING_LEN" in ch9.h instead of in usb.h.
>     Thanks for Alan's suggestion.
> Changes for v3:
>   - Rebase to 5.8-rc1 and resolve conflict.
> 
>  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(-)
> 
> diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
> index cb4950c..d0de016 100644
> --- a/drivers/usb/gadget/composite.c
> +++ b/drivers/usb/gadget/composite.c
> @@ -1041,7 +1041,7 @@ static void collect_langs(struct usb_gadget_strings **sp, __le16 *buf)
>  	while (*sp) {
>  		s = *sp;
>  		language = cpu_to_le16(s->language);
> -		for (tmp = buf; *tmp && tmp < &buf[126]; tmp++) {
> +		for (tmp = buf; *tmp && tmp < &buf[MAX_USB_STRING_LEN]; tmp++) {
>  			if (*tmp == language)
>  				goto repeat;
>  		}
> @@ -1116,7 +1116,7 @@ static int get_string(struct usb_composite_dev *cdev,
>  			collect_langs(sp, s->wData);
>  		}
>  
> -		for (len = 0; len <= 126 && s->wData[len]; len++)
> +		for (len = 0; len <= MAX_USB_STRING_LEN && s->wData[len]; len++)
>  			continue;
>  		if (!len)
>  			return -EINVAL;
> diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
> index 32b637e..70dd4ba 100644
> --- a/drivers/usb/gadget/configfs.c
> +++ b/drivers/usb/gadget/configfs.c
> @@ -115,7 +115,7 @@ static int usb_string_copy(const char *s, char **s_copy)
>  	char *str;
>  	char *copy = *s_copy;
>  	ret = strlen(s);
> -	if (ret > 126)
> +	if (ret > MAX_USB_STRING_LEN)
>  		return -EOVERFLOW;
>  
>  	str = kstrdup(s, GFP_KERNEL);
> diff --git a/drivers/usb/gadget/usbstring.c b/drivers/usb/gadget/usbstring.c
> index 7c24d1c..8a8d647 100644
> --- a/drivers/usb/gadget/usbstring.c
> +++ b/drivers/usb/gadget/usbstring.c
> @@ -55,9 +55,9 @@
>  		return -EINVAL;
>  
>  	/* string descriptors have length, tag, then UTF16-LE text */
> -	len = min ((size_t) 126, strlen (s->s));
> +	len = min((size_t)MAX_USB_STRING_LEN, strlen(s->s));
>  	len = utf8s_to_utf16s(s->s, len, UTF16_LITTLE_ENDIAN,
> -			(wchar_t *) &buf[2], 126);
> +			(wchar_t *) &buf[2], MAX_USB_STRING_LEN);
>  	if (len < 0)
>  		return -EINVAL;
>  	buf [0] = (len + 1) * 2;
> diff --git a/include/uapi/linux/usb/ch9.h b/include/uapi/linux/usb/ch9.h
> index 2b623f3..cc02d05 100644
> --- a/include/uapi/linux/usb/ch9.h
> +++ b/include/uapi/linux/usb/ch9.h
> @@ -364,6 +364,9 @@ struct usb_config_descriptor {
>  
>  /*-------------------------------------------------------------------------*/
>  
> +/* USB String descriptors can contain at most 126 characters. */
> +#define MAX_USB_STRING_LEN	126

Nit, as this is part of the userspace api, we should make this
"USB_MAX_STRING_LEN" as we should be using "USB_" for all exports here.

That seems to be the case already except for one really odd set of
"TEST_" defines, which I'll go fix up after this...

I will just hand-edit this patch to make that change so you don't have
to respin it again...

thanks,

greg k-h