[PATCH] drm: avoid passing null pointer to memset

[Rodrigo Vivi]

When cmd isn't IOC_IN | IOC_OUT a null "kdata" goes to "memset", which dereferences it.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi at gmail.com>
---
 drivers/gpu/drm/drm_drv.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 1490e76..5945920 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -452,8 +452,16 @@ long drm_ioctl(struct file *filp,
 				retcode = -EFAULT;
 				goto err_i1;
 			}
-		} else
+		} else {
+			if (!kdata) {
+				kdata = kmalloc(usize, GFP_KERNEL);
+		    		if (!kdata) {
+					retcode = -ENOMEM;
+					goto err_i1;
+				}
+			}
 			memset(kdata, 0, usize);
+		}
 
 		if (ioctl->flags & DRM_UNLOCKED)
 			retcode = func(dev, kdata, file_priv);
-- 
1.7.11.4