linux-kernel - [PATCH 4.19 098/134] drm/vkms: fix use-after-free when drm_gem_handle

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20190401170053.448431437@linuxfoundation.org>
Date:   Mon,  1 Apr 2019 19:02:14 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Rodrigo Siqueira <rodrigosiqueiramelo@...il.com>,
        Haneen Mohammed <hamohammed.sa@...il.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Chris Wilson <chris@...is-wilson.co.uk>,
        Eric Biggers <ebiggers@...gle.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>
Subject: [PATCH 4.19 098/134] drm/vkms: fix use-after-free when drm_gem_handle_create() fails

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Biggers <ebiggers@...gle.com>

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 <rodrigosiqueiramelo@...il.com>
Cc: Haneen Mohammed <hamohammed.sa@...il.com>
Cc: Daniel Vetter <daniel.vetter@...ll.ch>
Cc: Chris Wilson <chris@...is-wilson.co.uk>
Cc: stable@...r.kernel.org
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Reviewed-by: Chris Wilson <chris@...is-wilson.co.uk>
Reviewed-by: Rodrigo Siqueira <rodrigosiqueiramelo@...il.com>
Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@...il.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190226220858.214438-1-ebiggers@kernel.org
Signed-off-by: Maxime Ripard <maxime.ripard@...tlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/vkms/vkms_gem.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

--- 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(s
 
 	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;
 }