From 0612704b6f6ddf2ae223019c52148c5ac76cf70e Mon Sep 17 00:00:00 2001 From: Boris Brezillon Date: Fri, 31 Oct 2025 16:48:15 +0100 Subject: [PATCH] drm/panthor: Fix UAF on kernel BO VA nodes [ Upstream commit 98dd5143447af0ee33551776d8b2560c35d0bc4a ] 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: Lars-Ivar Hesselberg Simonsen Closes: https://gitlab.freedesktop.org/panfrost/linux/-/issues/57 Fixes: 8a1cc07578bf ("drm/panthor: Add GEM logical block") Signed-off-by: Boris Brezillon Reviewed-by: Liviu Dudau Link: https://patch.msgid.link/20251031154818.821054-2-boris.brezillon@collabora.com Signed-off-by: Liviu Dudau Signed-off-by: Sasha Levin --- drivers/gpu/drm/panthor/panthor_gem.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-) diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c index 3f43686f0195..14ed09d700f2 100644 --- a/drivers/gpu/drm/panthor/panthor_gem.c +++ b/drivers/gpu/drm/panthor/panthor_gem.c @@ -86,7 +86,6 @@ 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; @@ -94,18 +93,11 @@ 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); }