queue-5.0/drm-vgem-fix-use-after-free-when-drm_gem_handle_create-fails.patch

   1 From 21d2b122732318b48c10b7262e15595ce54511d3 Mon Sep 17 00:00:00 2001
   2 From: Eric Biggers <ebiggers@google.com>
   3 Date: Tue, 26 Feb 2019 13:44:51 -0800
   4 Subject: drm/vgem: fix use-after-free when drm_gem_handle_create() fails
   5
   6 From: Eric Biggers <ebiggers@google.com>
   7
   8 commit 21d2b122732318b48c10b7262e15595ce54511d3 upstream.
   9
  10 If drm_gem_handle_create() fails in vgem_gem_create(), then the
  11 drm_vgem_gem_object is freed twice: once when the reference is dropped
  12 by drm_gem_object_put_unlocked(), and again by __vgem_gem_destroy().
  13
  14 This was hit by syzkaller using fault injection.
  15
  16 Fix it by skipping the second free.
  17
  18 Reported-by: syzbot+e73f2fb5ed5a5df36d33@syzkaller.appspotmail.com
  19 Fixes: af33a9190d02 ("drm/vgem: Enable dmabuf import interfaces")
  20 Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
  21 Cc: Laura Abbott <labbott@redhat.com>
  22 Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
  23 Cc: stable@vger.kernel.org
  24 Signed-off-by: Eric Biggers <ebiggers@google.com>
  25 Acked-by: Laura Abbott <labbott@redhat.com>
  26 Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
  27 Link: https://patchwork.freedesktop.org/patch/msgid/20190226214451.195123-1-ebiggers@kernel.org
  28 Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
  29 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  30
  31 ---
  32  drivers/gpu/drm/vgem/vgem_drv.c |    6 +-----
  33  1 file changed, 1 insertion(+), 5 deletions(-)
  34
  35 --- a/drivers/gpu/drm/vgem/vgem_drv.c
  36 +++ b/drivers/gpu/drm/vgem/vgem_drv.c
  37 @@ -191,13 +191,9 @@ static struct drm_gem_object *vgem_gem_c
  38         ret = drm_gem_handle_create(file, &obj->base, handle);
  39         drm_gem_object_put_unlocked(&obj->base);
  40         if (ret)
  41 -               goto err;
  42 +               return ERR_PTR(ret);
  43
  44         return &obj->base;
  45 -
  46 -err:
  47 -       __vgem_gem_destroy(obj);
  48 -       return ERR_PTR(ret);
  49  }
  50
  51  static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev,