From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Biggers Subject: [PATCH v2] drm/vgem: fix use-after-free when drm_gem_handle_create() fails Date: Tue, 26 Feb 2019 13:44:51 -0800 Message-ID: <20190226214451.195123-1-ebiggers@kernel.org> References: <20190226213053.GC218103@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190226213053.GC218103@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: dri-devel@lists.freedesktop.org Cc: Chris Wilson , syzkaller-bugs , linux-kernel@vger.kernel.org, syzbot+e73f2fb5ed5a5df36d33@syzkaller.appspotmail.com, Laura Abbott , Daniel Vetter , stable@vger.kernel.org List-Id: dri-devel@lists.freedesktop.org From: Eric Biggers If drm_gem_handle_create() fails in vgem_gem_create(), then the drm_vgem_gem_object is freed twice: once when the reference is dropped by drm_gem_object_put_unlocked(), and again by __vgem_gem_destroy(). This was hit by syzkaller using fault injection. Fix it by skipping the second free. Reported-by: syzbot+e73f2fb5ed5a5df36d33@syzkaller.appspotmail.com Fixes: af33a9190d02 ("drm/vgem: Enable dmabuf import interfaces") Reviewed-by: Chris Wilson Cc: Laura Abbott Cc: Daniel Vetter Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers --- drivers/gpu/drm/vgem/vgem_drv.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c index 5930facd6d2d8..11a8f99ba18c5 100644 --- a/drivers/gpu/drm/vgem/vgem_drv.c +++ b/drivers/gpu/drm/vgem/vgem_drv.c @@ -191,13 +191,9 @@ static struct drm_gem_object *vgem_gem_create(struct drm_device *dev, ret = drm_gem_handle_create(file, &obj->base, handle); drm_gem_object_put_unlocked(&obj->base); if (ret) - goto err; + return ERR_PTR(ret); return &obj->base; - -err: - __vgem_gem_destroy(obj); - return ERR_PTR(ret); } static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev, -- 2.21.0.rc2.261.ga7da99ff1b-goog