drm: make drm_dev_set_unique() not use a format string

drm_dev_set_unique() uses a format string to define the unique name of a
device.  This feature is not used as currently all the calls to this
function either use "%s" as a format string or directly use
dev_name().

Even though this second kind of call does not introduce security
problems, because there cannot be "%" characters in dev_name() results,
gcc issues a warning when building with -Wformat-security flag
("warning: format string is not a string literal (potentially
insecure)").  This warning is useful to find real bugs like the one
fixed by commit 3958b79266b1 ("configfs: fix kernel infoleak through
user-controlled format string").  False positives which do not bring
an extra value make the work of finding real bugs harder.

Therefore remove the format-string feature from drm_dev_set_unique().

Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1449829228-4425-1-git-send-email-nicolas.iooss_linux@m4x.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 6 insertions, 11 deletions

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 7dd6728dd092..eaa4316f3c45 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -797,23 +797,18 @@ EXPORT_SYMBOL(drm_dev_unregister);
 /**
  * drm_dev_set_unique - Set the unique name of a DRM device
  * @dev: device of which to set the unique name
- * @fmt: format string for unique name
+ * @name: unique name
  *
- * Sets the unique name of a DRM device using the specified format string and
- * a variable list of arguments. Drivers can use this at driver probe time if
- * the unique name of the devices they drive is static.
+ * Sets the unique name of a DRM device using the specified string. Drivers
+ * can use this at driver probe time if the unique name of the devices they
+ * drive is static.
  *
  * Return: 0 on success or a negative error code on failure.
  */
-int drm_dev_set_unique(struct drm_device *dev, const char *fmt, ...)
+int drm_dev_set_unique(struct drm_device *dev, const char *name)
 {
-	va_list ap;
-
 	kfree(dev->unique);
-
-	va_start(ap, fmt);
-	dev->unique = kvasprintf(GFP_KERNEL, fmt, ap);
-	va_end(ap);
+	dev->unique = kstrdup(name, GFP_KERNEL);
 
 	return dev->unique ? 0 : -ENOMEM;
 }