From: Eric Biggers Date: Tue, 26 Feb 2019 22:08:58 +0000 (-0800) Subject: drm/vkms: fix use-after-free when drm_gem_handle_create() fails X-Git-Tag: v4.19.33~37 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=75f9e994b9fda979f542e8987bb9db9e2db82862;p=platform%2Fkernel%2Flinux-rpi.git drm/vkms: fix use-after-free when drm_gem_handle_create() fails commit 36b6c9ed45afe89045973e8dee1b004dd5372d40 upstream. If drm_gem_handle_create() fails in vkms_gem_create(), then the vkms_gem_object is freed twice: once when the reference is dropped by drm_gem_object_put_unlocked(), and again by the extra calls to drm_gem_object_release() and kfree(). Fix it by skipping the second release and free. This bug was originally found in the vgem driver by syzkaller using fault injection, but I noticed it's also present in the vkms driver. Fixes: 559e50fd34d1 ("drm/vkms: Add dumb operations") Cc: Rodrigo Siqueira Cc: Haneen Mohammed Cc: Daniel Vetter Cc: Chris Wilson Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers Reviewed-by: Chris Wilson Reviewed-by: Rodrigo Siqueira Signed-off-by: Rodrigo Siqueira Link: https://patchwork.freedesktop.org/patch/msgid/20190226220858.214438-1-ebiggers@kernel.org Signed-off-by: Maxime Ripard Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/gpu/drm/vkms/vkms_gem.c b/drivers/gpu/drm/vkms/vkms_gem.c index ca4a74e..ce39400 100644 --- a/drivers/gpu/drm/vkms/vkms_gem.c +++ b/drivers/gpu/drm/vkms/vkms_gem.c @@ -110,11 +110,8 @@ struct drm_gem_object *vkms_gem_create(struct drm_device *dev, ret = drm_gem_handle_create(file, &obj->gem, handle); drm_gem_object_put_unlocked(&obj->gem); - if (ret) { - drm_gem_object_release(&obj->gem); - kfree(obj); + if (ret) return ERR_PTR(ret); - } return &obj->gem; }