Commit 98dd5143 authored by Boris Brezillon's avatar Boris Brezillon Committed by Liviu Dudau
Browse files

drm/panthor: Fix UAF on kernel BO VA nodes 



If the MMU is down, panthor_vm_unmap_range() might return an error.
We expect the page table to be updated still, and if the MMU is blocked,
the rest of the GPU should be blocked too, so no risk of accessing
physical memory returned to the system (which the current code doesn't
cover for anyway).

Proceed with the rest of the cleanup instead of bailing out and leaving
the va_node inserted in the drm_mm, which leads to UAF when other
adjacent nodes are removed from the drm_mm tree.

Reported-by: default avatarLars-Ivar Hesselberg Simonsen <lars-ivar.simonsen@arm.com>
Closes: https://gitlab.freedesktop.org/panfrost/linux/-/issues/57


Fixes: 8a1cc075 ("drm/panthor: Add GEM logical block")
Signed-off-by: default avatarBoris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: default avatarLiviu Dudau <liviu.dudau@arm.com>
Link: https://patch.msgid.link/20251031154818.821054-2-boris.brezillon@collabora.com


Signed-off-by: default avatarLiviu Dudau <liviu.dudau@arm.com>
parent 08be57e6

drivers/gpu/drm/panthor/panthor_gem.c

+3 −11
Original line number Diff line number Diff line
@@ -87,7 +87,6 @@ static void panthor_gem_free_object(struct drm_gem_object *obj) 
void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo)

{

	struct panthor_vm *vm;

	int ret;



	if (IS_ERR_OR_NULL(bo))

		return;
@@ -95,18 +94,11 @@ void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo) 
	vm = bo->vm;

	panthor_kernel_bo_vunmap(bo);



	if (drm_WARN_ON(bo->obj->dev,

			to_panthor_bo(bo->obj)->exclusive_vm_root_gem != panthor_vm_root_gem(vm)))

		goto out_free_bo;



	ret = panthor_vm_unmap_range(vm, bo->va_node.start, bo->va_node.size);

	if (ret)

		goto out_free_bo;



	drm_WARN_ON(bo->obj->dev,

		    to_panthor_bo(bo->obj)->exclusive_vm_root_gem != panthor_vm_root_gem(vm));

	panthor_vm_unmap_range(vm, bo->va_node.start, bo->va_node.size);

	panthor_vm_free_va(vm, &bo->va_node);

	drm_gem_object_put(bo->obj);



out_free_bo:

	panthor_vm_put(vm);

	kfree(bo);

}