From: Ben Hutchings <ben@decadent.org.uk>
Date: Fri, 20 Jul 2018 01:30:24 +0100
Subject: usbip: Fix misuse of strncpy()
Bug-Debian: https://bugs.debian.org/897802
Forwarded: https://marc.info/?l=linux-usb&m=153213915806258

gcc 8 reports:

usbip_device_driver.c: In function ‘read_usb_vudc_device’:
usbip_device_driver.c:106:2: error: ‘strncpy’ specified bound 256 equals destination size [-Werror=stringop-truncation]
  strncpy(dev->path, path, SYSFS_PATH_MAX);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
usbip_device_driver.c:125:2: error: ‘strncpy’ specified bound 32 equals destination size [-Werror=stringop-truncation]
  strncpy(dev->busid, name, SYSFS_BUS_ID_SIZE);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I'm not convinced it makes sense to truncate the copied strings here,
but since we're already doing so let's ensure they're still null-
terminated.  We can't easily use strlcpy() here, so use snprintf().

usbip_common.c has the same problem.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
Index: linux/tools/usb/usbip/libsrc/usbip_common.c
===================================================================
--- linux.orig/tools/usb/usbip/libsrc/usbip_common.c
+++ linux/tools/usb/usbip/libsrc/usbip_common.c
@@ -226,8 +226,8 @@ int read_usb_device(struct udev_device *
 	path = udev_device_get_syspath(sdev);
 	name = udev_device_get_sysname(sdev);
 
-	strncpy(udev->path,  path,  SYSFS_PATH_MAX);
-	strncpy(udev->busid, name, SYSFS_BUS_ID_SIZE);
+	snprintf(udev->path, SYSFS_PATH_MAX, "%s", path);
+	snprintf(udev->busid, SYSFS_BUS_ID_SIZE, "%s", name);
 
 	sscanf(name, "%u-%u", &busnum, &devnum);
 	udev->busnum = busnum;
Index: linux/tools/usb/usbip/libsrc/usbip_device_driver.c
===================================================================
--- linux.orig/tools/usb/usbip/libsrc/usbip_device_driver.c
+++ linux/tools/usb/usbip/libsrc/usbip_device_driver.c
@@ -103,7 +103,7 @@ int read_usb_vudc_device(struct udev_dev
 	copy_descr_attr16(dev, &descr, idProduct);
 	copy_descr_attr16(dev, &descr, bcdDevice);
 
-	strncpy(dev->path, path, SYSFS_PATH_MAX);
+	snprintf(dev->path, SYSFS_PATH_MAX, "%s", path);
 
 	dev->speed = USB_SPEED_UNKNOWN;
 	speed = udev_device_get_sysattr_value(sdev, "current_speed");
@@ -122,7 +122,7 @@ int read_usb_vudc_device(struct udev_dev
 	dev->busnum = 0;
 
 	name = udev_device_get_sysname(plat);
-	strncpy(dev->busid, name, SYSFS_BUS_ID_SIZE);
+	snprintf(dev->busid, SYSFS_BUS_ID_SIZE, "%s", name);
 	return 0;
 err:
 	fclose(fd);