From 36b6c9ed45afe89045973e8dee1b004dd5372d40 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Tue, 26 Feb 2019 14:08:58 -0800
Subject: [PATCH] drm/vkms: fix use-after-free when drm_gem_handle_create() fails
Git-commit: 36b6c9ed45afe89045973e8dee1b004dd5372d40
Patch-mainline: v5.1-rc3
References: bsc#1111666
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 <rodrigosiqueiramelo@gmail.com>
Cc: Haneen Mohammed <hamohammed.sa@gmail.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190226220858.214438-1-ebiggers@kernel.org
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/gpu/drm/vkms/vkms_gem.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/vkms/vkms_gem.c b/drivers/gpu/drm/vkms/vkms_gem.c
index 138b0bb325cf..69048e73377d 100644
--- a/drivers/gpu/drm/vkms/vkms_gem.c
+++ b/drivers/gpu/drm/vkms/vkms_gem.c
@@ -111,11 +111,8 @@ 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;
}
--
2.16.4