[PATCH v2 1/2] drm: make drm_dev_set_unique() not use a format string

From: Nicolas Iooss
Date: Fri Dec 11 2015 - 05:26:55 EST


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@xxxxxxx>
---
v2: update drm_dev_set_unique() comment

drivers/gpu/drm/drm_drv.c | 17 ++++++-----------
drivers/gpu/drm/nouveau/nouveau_drm.c | 2 +-
drivers/gpu/drm/rockchip/rockchip_drm_drv.c | 2 +-
include/drm/drmP.h | 2 +-
4 files changed, 9 insertions(+), 14 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;
}
diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
index 1d3ee5179ab8..2d23f95f17ce 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -1046,7 +1046,7 @@ nouveau_platform_device_create(const struct nvkm_device_tegra_func *func,
goto err_free;
}

- err = drm_dev_set_unique(drm, "%s", dev_name(&pdev->dev));
+ err = drm_dev_set_unique(drm, dev_name(&pdev->dev));
if (err < 0)
goto err_free;

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
index f22e1e1ee64a..215d6c44af55 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
@@ -450,7 +450,7 @@ static int rockchip_drm_bind(struct device *dev)
if (!drm)
return -ENOMEM;

- ret = drm_dev_set_unique(drm, "%s", dev_name(dev));
+ ret = drm_dev_set_unique(drm, dev_name(dev));
if (ret)
goto err_free;

diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 0a271ca1f7c7..f14c25a6bbf2 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1059,7 +1059,7 @@ void drm_dev_ref(struct drm_device *dev);
void drm_dev_unref(struct drm_device *dev);
int drm_dev_register(struct drm_device *dev, unsigned long flags);
void drm_dev_unregister(struct drm_device *dev);
-int drm_dev_set_unique(struct drm_device *dev, const char *fmt, ...);
+int drm_dev_set_unique(struct drm_device *dev, const char *name);

struct drm_minor *drm_minor_acquire(unsigned int minor_id);
void drm_minor_release(struct drm_minor *minor);
--
2.6.3

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