[PATCH] drm: fix NULL pointer access by wrong ioctl

[Zhaowei Yuan]

If user uses wrong ioctl command with _IOC_NONE and argument size
greater than 0, it can cause NULL pointer access from memset of line
463. If _IOC_NONE, don't memset to 0 for kdata.

Signed-off-by: Zhaowei Yuan <zhaowei.yuan at samsung.com>
---
 drivers/gpu/drm/drm_drv.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
 mode change 100644 => 100755 drivers/gpu/drm/drm_drv.c

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
old mode 100644
new mode 100755
index 2ab782c..1a92bcb
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -459,8 +459,9 @@ long drm_ioctl(struct file *filp,
                                retcode = -EFAULT;
                                goto err_i1;
                        }
-               } else
+               } else if (cmd & IOC_OUT) {
                        memset(kdata, 0, usize);
+               }

                if (ioctl->flags & DRM_UNLOCKED)
                        retcode = func(dev, kdata, file_priv);
--
1.7.9.5