gpu/drm: Fix lock held when returning to user space.

We need to call drm_modeset_acquire_fini() when drm_atomic_state_alloc()
failed or call drm_modeset_acquire_init() after drm_atomic_state_alloc()
succeeded.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+6ea337c427f5083ebdf2@syzkaller.appspotmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1547115571-21219-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp

1 files changed, 1 insertions, 2 deletions

diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index c40889888a16..9a1f41adfc67 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -1296,12 +1296,11 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
                         (arg->flags & DRM_MODE_PAGE_FLIP_EVENT))
                 return -EINVAL;
 
-        drm_modeset_acquire_init(&ctx, DRM_MODESET_ACQUIRE_INTERRUPTIBLE);
-
         state = drm_atomic_state_alloc(dev);
         if (!state)
                 return -ENOMEM;
 
+        drm_modeset_acquire_init(&ctx, DRM_MODESET_ACQUIRE_INTERRUPTIBLE);
         state->acquire_ctx = &ctx;
         state->allow_modeset = !!(arg->flags & DRM_MODE_ATOMIC_ALLOW_MODESET);