drm/radeon: fix rare segfault

In gem idle/busy ioctl the radeon object was derefenced after
drm_gem_object_unreference_unlocked which in case the object
have been destroyed lead to use of a possibly free pointer with
possibly wrong data.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
index f28bd4b7ef98..21ec9f5653ce 100644
--- a/drivers/gpu/drm/radeon/radeon_gem.c
+++ b/drivers/gpu/drm/radeon/radeon_gem.c
@@ -292,6 +292,7 @@ int radeon_gem_mmap_ioctl(struct drm_device *dev, void *data,
 int radeon_gem_busy_ioctl(struct drm_device *dev, void *data,
                           struct drm_file *filp)
 {
+        struct radeon_device *rdev = dev->dev_private;
         struct drm_radeon_gem_busy *args = data;
         struct drm_gem_object *gobj;
         struct radeon_bo *robj;
@@ -317,13 +318,14 @@ int radeon_gem_busy_ioctl(struct drm_device *dev, void *data,
                 break;
         }
         drm_gem_object_unreference_unlocked(gobj);
-        r = radeon_gem_handle_lockup(robj->rdev, r);
+        r = radeon_gem_handle_lockup(rdev, r);
         return r;
 }
 
 int radeon_gem_wait_idle_ioctl(struct drm_device *dev, void *data,
                               struct drm_file *filp)
 {
+        struct radeon_device *rdev = dev->dev_private;
         struct drm_radeon_gem_wait_idle *args = data;
         struct drm_gem_object *gobj;
         struct radeon_bo *robj;
@@ -336,10 +338,10 @@ int radeon_gem_wait_idle_ioctl(struct drm_device *dev, void *data,
         robj = gem_to_radeon_bo(gobj);
         r = radeon_bo_wait(robj, NULL, false);
         /* callback hw specific functions if any */
-        if (robj->rdev->asic->ioctl_wait_idle)
-                robj->rdev->asic->ioctl_wait_idle(robj->rdev, robj);
+        if (rdev->asic->ioctl_wait_idle)
+                robj->rdev->asic->ioctl_wait_idle(rdev, robj);
         drm_gem_object_unreference_unlocked(gobj);
-        r = radeon_gem_handle_lockup(robj->rdev, r);
+        r = radeon_gem_handle_lockup(rdev, r);
         return r;
 }