From patchwork Tue Apr 26 16:42:46 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Potapenko X-Patchwork-Id: 12827500 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9CC62C433FE for ; Tue, 26 Apr 2022 16:45:07 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 316026B0096; Tue, 26 Apr 2022 12:45:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2C8248D0001; Tue, 26 Apr 2022 12:45:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 13FCA6B0099; Tue, 26 Apr 2022 12:45:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.25]) by kanga.kvack.org (Postfix) with ESMTP id 05C956B0096 for ; Tue, 26 Apr 2022 12:45:07 -0400 (EDT) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id DB5F780ABE for ; Tue, 26 Apr 2022 16:45:06 +0000 (UTC) X-FDA: 79399605012.02.946AA44 Received: from mail-ed1-f73.google.com (mail-ed1-f73.google.com [209.85.208.73]) by imf12.hostedemail.com (Postfix) with ESMTP id 0C03E40047 for ; Tue, 26 Apr 2022 16:44:57 +0000 (UTC) Received: by mail-ed1-f73.google.com with SMTP id n4-20020a5099c4000000b00418ed58d92fso10617559edb.0 for ; Tue, 26 Apr 2022 09:45:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=mDlUedrAZbNWp5ky59jIg6dQAqQa/OsCzADtdk11998=; b=YzWXjysgR42Q3TFVESmvN5pkk/chWv55MOWNS/6w5CgonTDe7EDOi6/dgov5acrkBk +eLpaTXxOwDMeDh/5NLJd2WaBWiomoLwEkXAYy/dGDvTLkfWpvwhhRdnoGBIUGURSa1L l9wqvDH8ai6JCL9QFA+PPkYwc0EQxgwx22SxZgPjsmRCAAgfTssPPlR7afWFGoadKtI2 Eron+27fhMxsLHiuvzn/2YPIzI2J1qzeOFB+DZVuNcwHxAUs4RAkE6xoNyDRZHC6y18/ xT82pJiOb+S+0kbNumQuG4h2OZz5fftBJtuJ9LtfEMIi/Y/tl9m44tBDJirEip3Wxd0t /VOA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=mDlUedrAZbNWp5ky59jIg6dQAqQa/OsCzADtdk11998=; b=2NdUtDDhcWpNOY5GwI1HkO7Gvo2wpwH6CsifEhYMPm5bZInBVj8RuzdMOtWZP8a9wZ QUZ6CicHh9W0q3SAHZt0jChY/MZdPVoDM72O7S4Xo+eJ1ApZuQtKgUOxhPmD25i4w1KQ 0EKPdx3lcJW5Ew/sLdGNT9bVyY8PtKPU4Dbm4/7EMfmU2K6OXmvAf56gQG5SErtsdx4w /N649WpUjwt5WbQIsXFdsuzx7J75QFUOUWqWo304HKTBYtV3Wf4JmLevI4NFroaJE1TH TiWBF1FJCqplnjCumQdx5P11slkOEqEUvKOU/pNXPjRvOxRC7i1Sd7iiwQ7j0hUDlVqa txHg== X-Gm-Message-State: AOAM530xPoExLyk0uXmg/aGE5U0xeMByHVksuO5gNNSxPJsr36QjGwQi SkTr5OudPPso9Rg4Xp0vVdcWGFbpkmc= X-Google-Smtp-Source: ABdhPJwjleNQ43dfYY89UGlYdB1Ku84OaO0hN9pyi13kzCfUmzv59quoT4hFyhlBNfthppVsEwYHULVNmjY= X-Received: from glider.muc.corp.google.com ([2a00:79e0:15:13:d580:abeb:bf6d:5726]) (user=glider job=sendgmr) by 2002:a05:6402:5114:b0:423:f33d:b3c with SMTP id m20-20020a056402511400b00423f33d0b3cmr25558297edd.199.1650991504954; Tue, 26 Apr 2022 09:45:04 -0700 (PDT) Date: Tue, 26 Apr 2022 18:42:46 +0200 In-Reply-To: <20220426164315.625149-1-glider@google.com> Message-Id: <20220426164315.625149-18-glider@google.com> Mime-Version: 1.0 References: <20220426164315.625149-1-glider@google.com> X-Mailer: git-send-email 2.36.0.rc2.479.g8af0fa9b8e-goog Subject: [PATCH v3 17/46] kmsan: mm: call KMSAN hooks from SLUB code From: Alexander Potapenko To: glider@google.com Cc: Alexander Viro , Andrew Morton , Andrey Konovalov , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Christoph Hellwig , Christoph Lameter , David Rientjes , Dmitry Vyukov , Eric Dumazet , Greg Kroah-Hartman , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jens Axboe , Joonsoo Kim , Kees Cook , Marco Elver , Mark Rutland , Matthew Wilcox , "Michael S. Tsirkin" , Pekka Enberg , Peter Zijlstra , Petr Mladek , Steven Rostedt , Thomas Gleixner , Vasily Gorbik , Vegard Nossum , Vlastimil Babka , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=YzWXjysg; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf12.hostedemail.com: domain of 3kCFoYgYKCI0x2zuv8x55x2v.t532z4BE-331Crt1.58x@flex--glider.bounces.google.com designates 209.85.208.73 as permitted sender) smtp.mailfrom=3kCFoYgYKCI0x2zuv8x55x2v.t532z4BE-331Crt1.58x@flex--glider.bounces.google.com X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 0C03E40047 X-Rspam-User: X-Stat-Signature: ff3i1z4r4mogtzq95upz97fb1ob9ip36 X-HE-Tag: 1650991497-901392 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: In order to report uninitialized memory coming from heap allocations KMSAN has to poison them unless they're created with __GFP_ZERO. It's handy that we need KMSAN hooks in the places where init_on_alloc/init_on_free initialization is performed. Signed-off-by: Alexander Potapenko --- v2: -- move the implementation of SLUB hooks here Link: https://linux-review.googlesource.com/id/I6954b386c5c5d7f99f48bb6cbcc74b75136ce86e --- include/linux/kmsan.h | 57 ++++++++++++++++++++++++++++++ mm/kmsan/hooks.c | 80 +++++++++++++++++++++++++++++++++++++++++++ mm/slab.h | 1 + mm/slub.c | 21 ++++++++++-- 4 files changed, 157 insertions(+), 2 deletions(-) diff --git a/include/linux/kmsan.h b/include/linux/kmsan.h index da41850b46cbd..ed3630068e2ef 100644 --- a/include/linux/kmsan.h +++ b/include/linux/kmsan.h @@ -16,6 +16,7 @@ #include struct page; +struct kmem_cache; #ifdef CONFIG_KMSAN @@ -73,6 +74,44 @@ void kmsan_free_page(struct page *page, unsigned int order); */ void kmsan_copy_page_meta(struct page *dst, struct page *src); +/** + * kmsan_slab_alloc() - Notify KMSAN about a slab allocation. + * @s: slab cache the object belongs to. + * @object: object pointer. + * @flags: GFP flags passed to the allocator. + * + * Depending on cache flags and GFP flags, KMSAN sets up the metadata of the + * newly created object, marking it as initialized or uninitialized. + */ +void kmsan_slab_alloc(struct kmem_cache *s, void *object, gfp_t flags); + +/** + * kmsan_slab_free() - Notify KMSAN about a slab deallocation. + * @s: slab cache the object belongs to. + * @object: object pointer. + * + * KMSAN marks the freed object as uninitialized. + */ +void kmsan_slab_free(struct kmem_cache *s, void *object); + +/** + * kmsan_kmalloc_large() - Notify KMSAN about a large slab allocation. + * @ptr: object pointer. + * @size: object size. + * @flags: GFP flags passed to the allocator. + * + * Similar to kmsan_slab_alloc(), but for large allocations. + */ +void kmsan_kmalloc_large(const void *ptr, size_t size, gfp_t flags); + +/** + * kmsan_kfree_large() - Notify KMSAN about a large slab deallocation. + * @ptr: object pointer. + * + * Similar to kmsan_slab_free(), but for large allocations. + */ +void kmsan_kfree_large(const void *ptr); + /** * kmsan_map_kernel_range_noflush() - Notify KMSAN about a vmap. * @start: start of vmapped range. @@ -139,6 +178,24 @@ static inline void kmsan_copy_page_meta(struct page *dst, struct page *src) { } +static inline void kmsan_slab_alloc(struct kmem_cache *s, void *object, + gfp_t flags) +{ +} + +static inline void kmsan_slab_free(struct kmem_cache *s, void *object) +{ +} + +static inline void kmsan_kmalloc_large(const void *ptr, size_t size, + gfp_t flags) +{ +} + +static inline void kmsan_kfree_large(const void *ptr) +{ +} + static inline void kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end, pgprot_t prot, diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c index 070756be70e3a..052e17b7a717d 100644 --- a/mm/kmsan/hooks.c +++ b/mm/kmsan/hooks.c @@ -26,6 +26,86 @@ * skipping effects of functions like memset() inside instrumented code. */ +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(); +} +EXPORT_SYMBOL(kmsan_slab_alloc); + +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(); +} +EXPORT_SYMBOL(kmsan_slab_free); + +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(); +} +EXPORT_SYMBOL(kmsan_kmalloc_large); + +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(); +} +EXPORT_SYMBOL(kmsan_kfree_large); + static unsigned long vmalloc_shadow(unsigned long addr) { return (unsigned long)kmsan_get_metadata((void *)addr, diff --git a/mm/slab.h b/mm/slab.h index 95eb34174c1bb..1276b83656091 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -751,6 +751,7 @@ static inline void slab_post_alloc_hook(struct kmem_cache *s, memset(p[i], 0, s->object_size); kmemleak_alloc_recursive(p[i], s->object_size, 1, s->flags, flags); + kmsan_slab_alloc(s, p[i], flags); } memcg_slab_post_alloc_hook(s, objcg, flags, size, p); diff --git a/mm/slub.c b/mm/slub.c index ed5c2c03a47aa..45082acaa6739 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include #include @@ -357,18 +358,28 @@ static void prefetch_freepointer(const struct kmem_cache *s, void *object) prefetchw(object + s->offset); } +/* + * When running under KMSAN, get_freepointer_safe() may return an uninitialized + * pointer value in the case the current thread loses the race for the next + * memory chunk in the freelist. In that case this_cpu_cmpxchg_double() in + * slab_alloc_node() will fail, so the uninitialized value won't be used, but + * KMSAN will still check all arguments of cmpxchg because of imperfect + * handling of inline assembly. + * To work around this problem, use kmsan_init() to force initialize the + * return value of get_freepointer_safe(). + */ static inline void *get_freepointer_safe(struct kmem_cache *s, void *object) { unsigned long freepointer_addr; void *p; if (!debug_pagealloc_enabled_static()) - return get_freepointer(s, object); + return kmsan_init(get_freepointer(s, object)); object = kasan_reset_tag(object); freepointer_addr = (unsigned long)object + s->offset; copy_from_kernel_nofault(&p, (void **)freepointer_addr, sizeof(p)); - return freelist_ptr(s, p, freepointer_addr); + return kmsan_init(freelist_ptr(s, p, freepointer_addr)); } static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp) @@ -1683,6 +1694,7 @@ static inline void *kmalloc_large_node_hook(void *ptr, size_t size, gfp_t flags) ptr = kasan_kmalloc_large(ptr, size, flags); /* As ptr might get tagged, call kmemleak hook after KASAN. */ kmemleak_alloc(ptr, size, 1, flags); + kmsan_kmalloc_large(ptr, size, flags); return ptr; } @@ -1690,12 +1702,14 @@ static __always_inline void kfree_hook(void *x) { kmemleak_free(x); kasan_kfree_large(x); + kmsan_kfree_large(x); } static __always_inline bool slab_free_hook(struct kmem_cache *s, void *x, bool init) { kmemleak_free_recursive(x, s->flags); + kmsan_slab_free(s, x); debug_check_no_locks_freed(x, s->object_size); @@ -3730,6 +3744,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, */ slab_post_alloc_hook(s, objcg, flags, size, p, slab_want_init_on_alloc(flags, s)); + return i; error: slub_put_cpu_ptr(s->cpu_slab); @@ -5898,6 +5913,7 @@ static char *create_unique_id(struct kmem_cache *s) p += sprintf(p, "%07u", s->size); BUG_ON(p > name + ID_STR_LENGTH - 1); + kmsan_unpoison_memory(name, p - name); return name; } @@ -5999,6 +6015,7 @@ static int sysfs_slab_alias(struct kmem_cache *s, const char *name) al->name = name; al->next = alias_list; alias_list = al; + kmsan_unpoison_memory(al, sizeof(struct saved_alias)); return 0; }