[PATCH] usbip: Fix misuse of strncpy()

[Ben Hutchings]

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 <b...@decadent.org.uk>
Cc: sta...@vger.kernel.org
---
 tools/usb/usbip/libsrc/usbip_common.c        |    4 ++--
 tools/usb/usbip/libsrc/usbip_device_driver.c |    4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

--- a/tools/usb/usbip/libsrc/usbip_common.c
+++ b/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;
--- a/tools/usb/usbip/libsrc/usbip_device_driver.c
+++ b/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);

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