This is a note to let you know that I've just added the patch titled
drm/syncobj: Fix use-after-free
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-syncobj-fix-use-after-free.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a37eef63bc9e16e06361b539e528058146af80ab Mon Sep 17 00:00:00 2001
From: Daniel Vetter <daniel.vetter@xxxxxxxx>
Date: Tue, 19 Jan 2021 14:03:18 +0100
Subject: drm/syncobj: Fix use-after-free
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From: Daniel Vetter <daniel.vetter@xxxxxxxx>
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@xxxxxxxxx>
Fixes: bc9c80fe01a2 ("drm/syncobj: use the timeline point in drm_syncobj_find_fence v4")
Reviewed-by: Christian König <christian.koenig@xxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Maxime Ripard <mripard@xxxxxxxxxx>
Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: <stable@xxxxxxxxxxxxxxx> # v5.2+
Link: https://patchwork.freedesktop.org/patch/msgid/20210119130318.615145-1-daniel.vetter@xxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -326,19 +326,18 @@ 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;
@@ -370,6 +369,9 @@ 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);
Patches currently in stable-queue which might be from daniel.vetter@xxxxxxxx are
queue-5.4/drm-syncobj-fix-use-after-free.patch
queue-5.4/drm-atomic-put-state-on-error-path.patch
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