// SPDX-License-Identifier: GPL-2.0 /* * KMSAN hooks for kernel subsystems. * * These functions handle creation of KMSAN metadata for memory allocations. * * Copyright (C) 2018-2022 Google LLC * Author: Alexander Potapenko * */ #include #include #include #include #include #include #include #include "../internal.h" #include "../slab.h" #include "kmsan.h" /* * Instrumented functions shouldn't be called under * kmsan_enter_runtime()/kmsan_leave_runtime(), because this will lead to * skipping effects of functions like memset() inside instrumented code. */ void kmsan_task_create(struct task_struct *task) { kmsan_enter_runtime(); kmsan_internal_task_create(task); kmsan_leave_runtime(); } void kmsan_task_exit(struct task_struct *task) { struct kmsan_ctx *ctx = &task->kmsan_ctx; if (!kmsan_enabled || kmsan_in_runtime()) return; ctx->allow_reporting = false; } void kmsan_slab_alloc(struct kmem_cache *s, void *object, gfp_t flags) { if (unlikely(object == NULL)) return; if (!kmsan_enabled || kmsan_in_runtime()) return; /* * There's a ctor or this is an RCU cache - do nothing. The memory * status hasn't changed since last use. */ if (s->ctor || (s->flags & SLAB_TYPESAFE_BY_RCU)) return; kmsan_enter_runtime(); if (flags & __GFP_ZERO) kmsan_internal_unpoison_memory(object, s->object_size, KMSAN_POISON_CHECK); else kmsan_internal_poison_memory(object, s->object_size, flags, KMSAN_POISON_CHECK); kmsan_leave_runtime(); } void kmsan_slab_free(struct kmem_cache *s, void *object) { if (!kmsan_enabled || kmsan_in_runtime()) return; /* RCU slabs could be legally used after free within the RCU period */ if (unlikely(s->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON))) return; /* * If there's a constructor, freed memory must remain in the same state * until the next allocation. We cannot save its state to detect * use-after-free bugs, instead we just keep it unpoisoned. */ if (s->ctor) return; kmsan_enter_runtime(); kmsan_internal_poison_memory(object, s->object_size, GFP_KERNEL, KMSAN_POISON_CHECK | KMSAN_POISON_FREE); kmsan_leave_runtime(); } void kmsan_kmalloc_large(const void *ptr, size_t size, gfp_t flags) { if (unlikely(ptr == NULL)) return; if (!kmsan_enabled || kmsan_in_runtime()) return; kmsan_enter_runtime(); if (flags & __GFP_ZERO) kmsan_internal_unpoison_memory((void *)ptr, size, /*checked*/ true); else kmsan_internal_poison_memory((void *)ptr, size, flags, KMSAN_POISON_CHECK); kmsan_leave_runtime(); } void kmsan_kfree_large(const void *ptr) { struct page *page; if (!kmsan_enabled || kmsan_in_runtime()) return; kmsan_enter_runtime(); page = virt_to_head_page((void *)ptr); KMSAN_WARN_ON(ptr != page_address(page)); kmsan_internal_poison_memory((void *)ptr, PAGE_SIZE << compound_order(page), GFP_KERNEL, KMSAN_POISON_CHECK | KMSAN_POISON_FREE); kmsan_leave_runtime(); } static unsigned long vmalloc_shadow(unsigned long addr) { return (unsigned long)kmsan_get_metadata((void *)addr, KMSAN_META_SHADOW); } static unsigned long vmalloc_origin(unsigned long addr) { return (unsigned long)kmsan_get_metadata((void *)addr, KMSAN_META_ORIGIN); } void kmsan_vunmap_range_noflush(unsigned long start, unsigned long end) { __vunmap_range_noflush(vmalloc_shadow(start), vmalloc_shadow(end)); __vunmap_range_noflush(vmalloc_origin(start), vmalloc_origin(end)); flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end)); flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end)); } /* * This function creates new shadow/origin pages for the physical pages mapped * into the virtual memory. If those physical pages already had shadow/origin, * those are ignored. */ void kmsan_ioremap_page_range(unsigned long start, unsigned long end, phys_addr_t phys_addr, pgprot_t prot, unsigned int page_shift) { gfp_t gfp_mask = GFP_KERNEL | __GFP_ZERO; struct page *shadow, *origin; unsigned long off = 0; int nr; if (!kmsan_enabled || kmsan_in_runtime()) return; nr = (end - start) / PAGE_SIZE; kmsan_enter_runtime(); for (int i = 0; i < nr; i++, off += PAGE_SIZE) { shadow = alloc_pages(gfp_mask, 1); origin = alloc_pages(gfp_mask, 1); __vmap_pages_range_noflush( vmalloc_shadow(start + off), vmalloc_shadow(start + off + PAGE_SIZE), prot, &shadow, PAGE_SHIFT); __vmap_pages_range_noflush( vmalloc_origin(start + off), vmalloc_origin(start + off + PAGE_SIZE), prot, &origin, PAGE_SHIFT); } flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end)); flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end)); kmsan_leave_runtime(); } void kmsan_iounmap_page_range(unsigned long start, unsigned long end) { unsigned long v_shadow, v_origin; struct page *shadow, *origin; int nr; if (!kmsan_enabled || kmsan_in_runtime()) return; nr = (end - start) / PAGE_SIZE; kmsan_enter_runtime(); v_shadow = (unsigned long)vmalloc_shadow(start); v_origin = (unsigned long)vmalloc_origin(start); for (int i = 0; i < nr; i++, v_shadow += PAGE_SIZE, v_origin += PAGE_SIZE) { shadow = kmsan_vmalloc_to_page_or_null((void *)v_shadow); origin = kmsan_vmalloc_to_page_or_null((void *)v_origin); __vunmap_range_noflush(v_shadow, vmalloc_shadow(end)); __vunmap_range_noflush(v_origin, vmalloc_origin(end)); if (shadow) __free_pages(shadow, 1); if (origin) __free_pages(origin, 1); } flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end)); flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end)); kmsan_leave_runtime(); } /* Functions from kmsan-checks.h follow. */ void kmsan_poison_memory(const void *address, size_t size, gfp_t flags) { if (!kmsan_enabled || kmsan_in_runtime()) return; kmsan_enter_runtime(); /* The users may want to poison/unpoison random memory. */ kmsan_internal_poison_memory((void *)address, size, flags, KMSAN_POISON_NOCHECK); kmsan_leave_runtime(); } EXPORT_SYMBOL(kmsan_poison_memory); void kmsan_unpoison_memory(const void *address, size_t size) { unsigned long ua_flags; if (!kmsan_enabled || kmsan_in_runtime()) return; ua_flags = user_access_save(); kmsan_enter_runtime(); /* The users may want to poison/unpoison random memory. */ kmsan_internal_unpoison_memory((void *)address, size, KMSAN_POISON_NOCHECK); kmsan_leave_runtime(); user_access_restore(ua_flags); } EXPORT_SYMBOL(kmsan_unpoison_memory); void kmsan_check_memory(const void *addr, size_t size) { if (!kmsan_enabled) return; return kmsan_internal_check_memory((void *)addr, size, /*user_addr*/ 0, REASON_ANY); } EXPORT_SYMBOL(kmsan_check_memory);