releases/4.19.32/drm-reorder-set_property_atomic-to-avoid-returning-with-an-active-ww_ctx.patch

   1 From 227ad6d957898a88b1746e30234ece64d305f066 Mon Sep 17 00:00:00 2001
   2 From: Chris Wilson <chris@chris-wilson.co.uk>
   3 Date: Sun, 30 Dec 2018 12:28:42 +0000
   4 Subject: drm: Reorder set_property_atomic to avoid returning with an active ww_ctx
   5
   6 From: Chris Wilson <chris@chris-wilson.co.uk>
   7
   8 commit 227ad6d957898a88b1746e30234ece64d305f066 upstream.
   9
  10 Delay the drm_modeset_acquire_init() until after we check for an
  11 allocation failure so that we can return immediately upon error without
  12 having to unwind.
  13
  14 WARNING: lock held when returning to user space!
  15 4.20.0+ #174 Not tainted
  16 ------------------------------------------------
  17 syz-executor556/8153 is leaving the kernel with locks still held!
  18 1 lock held by syz-executor556/8153:
  19   #0: 000000005100c85c (crtc_ww_class_acquire){+.+.}, at:
  20 set_property_atomic+0xb3/0x330 drivers/gpu/drm/drm_mode_object.c:462
  21
  22 Reported-by: syzbot+6ea337c427f5083ebdf2@syzkaller.appspotmail.com
  23 Fixes: 144a7999d633 ("drm: Handle properties in the core for atomic drivers")
  24 Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
  25 Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
  26 Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
  27 Cc: Sean Paul <sean@poorly.run>
  28 Cc: David Airlie <airlied@linux.ie>
  29 Cc: <stable@vger.kernel.org> # v4.14+
  30 Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
  31 Link: https://patchwork.freedesktop.org/patch/msgid/20181230122842.21917-1-chris@chris-wilson.co.uk
  32 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  33
  34 ---
  35  drivers/gpu/drm/drm_mode_object.c |    5 +++--
  36  1 file changed, 3 insertions(+), 2 deletions(-)
  37
  38 --- a/drivers/gpu/drm/drm_mode_object.c
  39 +++ b/drivers/gpu/drm/drm_mode_object.c
  40 @@ -458,12 +458,13 @@ static int set_property_atomic(struct dr
  41         struct drm_modeset_acquire_ctx ctx;
  42         int ret;
  43
  44 -       drm_modeset_acquire_init(&ctx, 0);
  45 -
  46         state = drm_atomic_state_alloc(dev);
  47         if (!state)
  48                 return -ENOMEM;
  49 +
  50 +       drm_modeset_acquire_init(&ctx, 0);
  51         state->acquire_ctx = &ctx;
  52 +
  53  retry:
  54         if (prop == state->dev->mode_config.dpms_property) {
  55                 if (obj->type != DRM_MODE_OBJECT_CONNECTOR) {