1 files changed, 19 insertions, 6 deletions

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 90288ec7c284..84da748555bc 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -55,6 +55,9 @@
 static int drm_version(struct drm_device *dev, void *data,
                        struct drm_file *file_priv);
 
+#define DRM_IOCTL_DEF(ioctl, _func, _flags) \
+        [DRM_IOCTL_NR(ioctl)] = {.cmd = ioctl, .func = _func, .flags = _flags, .cmd_drv = 0}
+
 /** Ioctl table */
 static struct drm_ioctl_desc drm_ioctls[] = {
         DRM_IOCTL_DEF(DRM_IOCTL_VERSION, drm_version, 0),
@@ -421,6 +424,7 @@ long drm_ioctl(struct file *filp,
         int retcode = -EINVAL;
         char stack_kdata[128];
         char *kdata = NULL;
+        unsigned int usize, asize;
 
         dev = file_priv->minor->dev;
         atomic_inc(&dev->ioctl_count);
@@ -436,11 +440,18 @@ long drm_ioctl(struct file *filp,
             ((nr < DRM_COMMAND_BASE) || (nr >= DRM_COMMAND_END)))
                 goto err_i1;
         if ((nr >= DRM_COMMAND_BASE) && (nr < DRM_COMMAND_END) &&
-            (nr < DRM_COMMAND_BASE + dev->driver->num_ioctls))
+            (nr < DRM_COMMAND_BASE + dev->driver->num_ioctls)) {
+                u32 drv_size;
                 ioctl = &dev->driver->ioctls[nr - DRM_COMMAND_BASE];
+                drv_size = _IOC_SIZE(ioctl->cmd_drv);
+                usize = asize = _IOC_SIZE(cmd);
+                if (drv_size > asize)
+                        asize = drv_size;
+        }
         else if ((nr >= DRM_COMMAND_END) || (nr < DRM_COMMAND_BASE)) {
                 ioctl = &drm_ioctls[nr];
                 cmd = ioctl->cmd;
+                usize = asize = _IOC_SIZE(cmd);
         } else
                 goto err_i1;
 
@@ -460,10 +471,10 @@ long drm_ioctl(struct file *filp,
                 retcode = -EACCES;
         } else {
                 if (cmd & (IOC_IN | IOC_OUT)) {
-                        if (_IOC_SIZE(cmd) <= sizeof(stack_kdata)) {
+                        if (asize <= sizeof(stack_kdata)) {
                                 kdata = stack_kdata;
                         } else {
-                                kdata = kmalloc(_IOC_SIZE(cmd), GFP_KERNEL);
+                                kdata = kmalloc(asize, GFP_KERNEL);
                                 if (!kdata) {
                                         retcode = -ENOMEM;
                                         goto err_i1;
@@ -473,11 +484,13 @@ long drm_ioctl(struct file *filp,
 
                 if (cmd & IOC_IN) {
                         if (copy_from_user(kdata, (void __user *)arg,
-                                           _IOC_SIZE(cmd)) != 0) {
+                                           usize) != 0) {
                                 retcode = -EFAULT;
                                 goto err_i1;
                         }
-                }
+                } else
+                        memset(kdata, 0, usize);
+
                 if (ioctl->flags & DRM_UNLOCKED)
                         retcode = func(dev, kdata, file_priv);
                 else {
@@ -488,7 +501,7 @@ long drm_ioctl(struct file *filp,
 
                 if (cmd & IOC_OUT) {
                         if (copy_to_user((void __user *)arg, kdata,
-                                         _IOC_SIZE(cmd)) != 0)
+                                         usize) != 0)
                                 retcode = -EFAULT;
                 }
         }