staging/usbip: userspace - fix usbipd SIGSEGV from refresh_exported_devices()

refresh_exported_devices() doesn't check udev_device_new_from_syspath()
return value and passed in null dev to udev_device_get_driver() resulting
in a segmentation fault. Change it to check for null return value from
both udev_device_new_from_syspath() and udev_device_get_driver().

Signed-off-by: Shuah Khan <shuah.kh@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/usbip/userspace/libsrc/usbip_host_driver.c b/drivers/staging/usbip/userspace/libsrc/usbip_host_driver.c
index c5bf60b..92caef7 100644 (file)
--- a/drivers/staging/usbip/userspace/libsrc/usbip_host_driver.c
+++ b/drivers/staging/usbip/userspace/libsrc/usbip_host_driver.c
@@ -118,6 +118,7 @@ static int refresh_exported_devices(void)
        struct udev_list_entry *devices, *dev_list_entry;
        struct udev_device *dev;
        const char *path;
+       const char *driver;
 
        enumerate = udev_enumerate_new(udev_context);
        udev_enumerate_add_match_subsystem(enumerate, "usb");
@@ -128,10 +129,12 @@ static int refresh_exported_devices(void)
        udev_list_entry_foreach(dev_list_entry, devices) {
                path = udev_list_entry_get_name(dev_list_entry);
                dev = udev_device_new_from_syspath(udev_context, path);
+               if (dev == NULL)
+                       continue;
 
                /* Check whether device uses usbip-host driver. */
-               if (!strcmp(udev_device_get_driver(dev),
-                           USBIP_HOST_DRV_NAME)) {
+               driver = udev_device_get_driver(dev);
+               if (driver != NULL && !strcmp(driver, USBIP_HOST_DRV_NAME)) {
                        edev = usbip_exported_device_new(path);
                        if (!edev) {
                                dbg("usbip_exported_device_new failed");