From: Dave Airlie airlied@redhat.com
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@redhat.com Fixes: 11e451e74050 ("drm/nouveau: remove fence wait code from deferred client work handler") Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie airlied@redhat.com Link: https://lore.kernel.org/dri-devel/20230615024008.1600281-1-airlied@gmail.com... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 @@ -124,10 +124,16 @@ 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