From a76ab17ac82c6bb32926300194e424993aab7bf1 Mon Sep 17 00:00:00 2001 From: Matthew Auld Date: Wed, 14 Aug 2024 12:01:30 +0100 Subject: [PATCH] drm/xe: prevent UAF around preempt fence BugLink: https://bugs.launchpad.net/bugs/2084225 [ Upstream commit 730b72480e29f63fd644f5fa57c9d46109428953 ] The fence lock is part of the queue, therefore in the current design anything locking the fence should then also hold a ref to the queue to prevent the queue from being freed. However, currently it looks like we signal the fence and then drop the queue ref, but if something is waiting on the fence, the waiter is kicked to wake up at some later point, where upon waking up it first grabs the lock before checking the fence state. But if we have already dropped the queue ref, then the lock might already be freed as part of the queue, leading to uaf. To prevent this, move the fence lock into the fence itself so we don't run into lifetime issues. Alternative might be to have device level lock, or only release the queue in the fence release callback, however that might require pushing to another worker to avoid locking issues. Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs") References: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2454 References: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2342 References: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2020 Signed-off-by: Matthew Auld Cc: Matthew Brost Cc: # v6.8+ Reviewed-by: Matthew Brost Link: https://patchwork.freedesktop.org/patch/msgid/20240814110129.825847-2-matthew.auld@intel.com (cherry picked from commit 7116c35aacedc38be6d15bd21b2fc936eed0008b) Signed-off-by: Rodrigo Vivi Signed-off-by: Sasha Levin [koichiroden: Adjusted context due to missing commit: 6240c2c43fd0 ("drm/xe: Document nested struct members according to guidelines")] Signed-off-by: Koichiro Den Signed-off-by: Stefan Bader --- drivers/gpu/drm/xe/xe_exec_queue.c | 1 - drivers/gpu/drm/xe/xe_exec_queue_types.h | 2 -- drivers/gpu/drm/xe/xe_preempt_fence.c | 3 ++- drivers/gpu/drm/xe/xe_preempt_fence_types.h | 2 ++ 4 files changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/xe/xe_exec_queue.c b/drivers/gpu/drm/xe/xe_exec_queue.c index 9052c9d8f73c..8a89d178dd07 100644 --- a/drivers/gpu/drm/xe/xe_exec_queue.c +++ b/drivers/gpu/drm/xe/xe_exec_queue.c @@ -616,7 +616,6 @@ int xe_exec_queue_create_ioctl(struct drm_device *dev, void *data, if (xe_vm_in_preempt_fence_mode(vm)) { q->lr.context = dma_fence_context_alloc(1); - spin_lock_init(&q->lr.lock); err = xe_vm_add_compute_exec_queue(vm, q); if (XE_IOCTL_DBG(xe, err)) diff --git a/drivers/gpu/drm/xe/xe_exec_queue_types.h b/drivers/gpu/drm/xe/xe_exec_queue_types.h index 77db99f3f944..9ce2601f8a04 100644 --- a/drivers/gpu/drm/xe/xe_exec_queue_types.h +++ b/drivers/gpu/drm/xe/xe_exec_queue_types.h @@ -148,8 +148,6 @@ struct xe_exec_queue { u32 seqno; /** @link: link into VM's list of exec queues */ struct list_head link; - /** @lock: preemption fences lock */ - spinlock_t lock; } lr; /** @ops: submission backend exec queue operations */ diff --git a/drivers/gpu/drm/xe/xe_preempt_fence.c b/drivers/gpu/drm/xe/xe_preempt_fence.c index 3c596303e97a..11ccbe029dd4 100644 --- a/drivers/gpu/drm/xe/xe_preempt_fence.c +++ b/drivers/gpu/drm/xe/xe_preempt_fence.c @@ -128,8 +128,9 @@ xe_preempt_fence_arm(struct xe_preempt_fence *pfence, struct xe_exec_queue *q, { list_del_init(&pfence->link); pfence->q = xe_exec_queue_get(q); + spin_lock_init(&pfence->lock); dma_fence_init(&pfence->base, &preempt_fence_ops, - &q->lr.lock, context, seqno); + &pfence->lock, context, seqno); return &pfence->base; } diff --git a/drivers/gpu/drm/xe/xe_preempt_fence_types.h b/drivers/gpu/drm/xe/xe_preempt_fence_types.h index b54b5c29b533..312c3372a49f 100644 --- a/drivers/gpu/drm/xe/xe_preempt_fence_types.h +++ b/drivers/gpu/drm/xe/xe_preempt_fence_types.h @@ -25,6 +25,8 @@ struct xe_preempt_fence { struct xe_exec_queue *q; /** @preempt_work: work struct which issues preemption */ struct work_struct preempt_work; + /** @lock: dma-fence fence lock */ + spinlock_t lock; /** @error: preempt fence is in error state */ int error; };