This is a note to let you know that I've just added the patch titled
nouveau: fix client work fence deletion race
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:
nouveau-fix-client-work-fence-deletion-race.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 c8a5d5ea3ba6a18958f8d76430e4cd68eea33943 Mon Sep 17 00:00:00 2001
From: Dave Airlie <airlied@xxxxxxxxxx>
Date: Thu, 15 Jun 2023 12:22:11 +1000
Subject: nouveau: fix client work fence deletion race
From: Dave Airlie <airlied@xxxxxxxxxx>
commit c8a5d5ea3ba6a18958f8d76430e4cd68eea33943 upstream.
This seems to have existed for ever but is now more apparant after
commit 9bff18d13473 ("drm/ttm: use per BO cleanup workers")
My analysis: two threads are running, one in the irq signalling the
fence, in dma_fence_signal_timestamp_locked, it has done the
DMA_FENCE_FLAG_SIGNALLED_BIT setting, but hasn't yet reached the
callbacks.
The second thread in nouveau_cli_work_ready, where it sees the fence is
signalled, so then puts the fence, cleanups the object and frees the
work item, which contains the callback.
Thread one goes again and tries to call the callback and causes the
use-after-free.
Proposed fix: lock the fence signalled check in nouveau_cli_work_ready,
so either the callbacks are done or the memory is freed.
Reviewed-by: Karol Herbst <kherbst@xxxxxxxxxx>
Fixes: 11e451e74050 ("drm/nouveau: remove fence wait code from deferred client work handler")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx>
Link: https://lore.kernel.org/dri-devel/20230615024008.1600281-1-airlied@xxxxxxxxx/
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/nouveau/nouveau_drm.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -123,10 +123,16 @@ nouveau_name(struct drm_device *dev)
static inline bool
nouveau_cli_work_ready(struct dma_fence *fence)
{
- if (!dma_fence_is_signaled(fence))
- return false;
- dma_fence_put(fence);
- return true;
+ bool ret = true;
+
+ spin_lock_irq(fence->lock);
+ if (!dma_fence_is_signaled_locked(fence))
+ ret = false;
+ spin_unlock_irq(fence->lock);
+
+ if (ret == true)
+ dma_fence_put(fence);
+ return ret;
}
static void
Patches currently in stable-queue which might be from airlied@xxxxxxxxxx are
queue-5.4/nouveau-fix-client-work-fence-deletion-race.patch
