linux-kernel - [PATCH 5.10 029/199] drm/syncobj: Fix use-after-free

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: <20210125183217.485039867@linuxfoundation.org>
Date:   Mon, 25 Jan 2021 19:37:31 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Daniel Vetter <daniel.vetter@...el.com>,
        Christian König <christian.koenig@....com>,
        Lionel Landwerlin <lionel.g.landwerlin@...el.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH 5.10 029/199] drm/syncobj: Fix use-after-free

From: Daniel Vetter <daniel.vetter@...ll.ch>

commit a37eef63bc9e16e06361b539e528058146af80ab upstream.

While reviewing Christian's annotation patch I noticed that we have a
user-after-free for the WAIT_FOR_SUBMIT case: We drop the syncobj
reference before we've completed the waiting.

Of course usually there's nothing bad happening here since userspace
keeps the reference, but we can't rely on userspace to play nice here!

Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
Fixes: bc9c80fe01a2 ("drm/syncobj: use the timeline point in drm_syncobj_find_fence v4")
Reviewed-by: Christian König <christian.koenig@....com>
Cc: Christian König <christian.koenig@....com>
Cc: Lionel Landwerlin <lionel.g.landwerlin@...el.com>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
Cc: Maxime Ripard <mripard@...nel.org>
Cc: Thomas Zimmermann <tzimmermann@...e.de>
Cc: David Airlie <airlied@...ux.ie>
Cc: Daniel Vetter <daniel@...ll.ch>
Cc: dri-devel@...ts.freedesktop.org
Cc: <stable@...r.kernel.org> # v5.2+
Link: https://patchwork.freedesktop.org/patch/msgid/20210119130318.615145-1-daniel.vetter@ffwll.ch
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/drm_syncobj.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -388,19 +388,18 @@ int drm_syncobj_find_fence(struct drm_fi
 		return -ENOENT;
 
 	*fence = drm_syncobj_fence_get(syncobj);
-	drm_syncobj_put(syncobj);
 
 	if (*fence) {
 		ret = dma_fence_chain_find_seqno(fence, point);
 		if (!ret)
-			return 0;
+			goto out;
 		dma_fence_put(*fence);
 	} else {
 		ret = -EINVAL;
 	}
 
 	if (!(flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT))
-		return ret;
+		goto out;
 
 	memset(&wait, 0, sizeof(wait));
 	wait.task = current;
@@ -432,6 +431,9 @@ int drm_syncobj_find_fence(struct drm_fi
 	if (wait.node.next)
 		drm_syncobj_remove_wait(syncobj, &wait);
 
+out:
+	drm_syncobj_put(syncobj);
+
 	return ret;
 }
 EXPORT_SYMBOL(drm_syncobj_find_fence);