From patchwork Fri Jul 1 14:22:40 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Potapenko X-Patchwork-Id: 12903372 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 313E9C43334 for ; Fri, 1 Jul 2022 14:24:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6E4E46B0088; Fri, 1 Jul 2022 10:23:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 66D4B6B0089; Fri, 1 Jul 2022 10:23:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 499146B008A; Fri, 1 Jul 2022 10:23:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 38C7D6B0088 for ; Fri, 1 Jul 2022 10:23:59 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 0C88620DFE for ; Fri, 1 Jul 2022 14:23:59 +0000 (UTC) X-FDA: 79638750198.03.832E65F Received: from mail-ej1-f74.google.com (mail-ej1-f74.google.com [209.85.218.74]) by imf19.hostedemail.com (Postfix) with ESMTP id A97E71A0039 for ; Fri, 1 Jul 2022 14:23:58 +0000 (UTC) Received: by mail-ej1-f74.google.com with SMTP id e20-20020a170906315400b007262bd0111eso841882eje.9 for ; Fri, 01 Jul 2022 07:23:58 -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=yQ768gKjsg7o2qhom6fXRmA7hEqZpzUb/NLIF5UbCVk=; b=ilZQasgNcrZJU5SMLJZGlURLt0pZ82ORL0+V8GocPsRlZs6tRnEGLVOfls8cUZJtgR 0R9M5BhBsomSj6OV1JKUmUwDFagJq1aNYwCqXEMTv4xgB5j2Y8jx/7HCM8Zcnoy1skVZ dgZc5GlmMfXmNgGLxm8ewEotHX/gNzlolDo6mNcw2gS0YiH3R1PNCs+f2m/a2DIemvAz 0eSoyaqeLDV//5dVrVYvDUiFjY6VFUjBaQJQh/0o6dwhxb3psYS4+4I1UgkFHt0hyqY/ 9vnPZRdQC2MezrZyNlxfyeuVLepfrXiJmU5ZUHS2hiJDRKCT9K/pC9q4//yJD4fIKNY/ z5qw== 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=yQ768gKjsg7o2qhom6fXRmA7hEqZpzUb/NLIF5UbCVk=; b=cP/6VR2o4OMMbAa0LKWUIJRwBmS4gw2KqeSbj2oxJaPhh1FcE6lWDfrJSnh684AyVB 5RnKZ60wpAFZNdf7Uh3rIatOlMm3Py52keEvGb0ygXa7JsiPyFbvco4bu+7i/WVdjQY0 2/9cpCdwbCjv7rmnRA34X0Z2OElQPh00DvW5Bme5A2LHscBJHsyoMVnn1+0hTbbVKsUU rHRJm2D05crX0E4slYeVx8NwC2up2Mbo4FDRSu0CSvIwm3VjbCi/tHsUaHcbGQQCG441 WxU7h7PDmWFux9XWNSYACv1OUVexbm1XKrf+3hfSVOAVBKtKCYWCm6n+a9ZOfnz61TT9 Wgmw== X-Gm-Message-State: AJIora80rDoc5il2eZGYNduRuwEYxkoSOZDYMMbrXtcGPWn9BQfCOsUE iqdyox0GMDNa/GrJujdJ7W8i2+N2kEE= X-Google-Smtp-Source: AGRyM1sm+6FJrp4kZ/TS4caUm7SvU0ZnpXFWFSa4DDFgO1nCu3BLqphLUK9DTM/B/KuGGGUeghZwZi10Euw= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:a6f5:f713:759c:abb6]) (user=glider job=sendgmr) by 2002:a05:6402:4410:b0:434:f35f:132e with SMTP id y16-20020a056402441000b00434f35f132emr19195845eda.215.1656685437446; Fri, 01 Jul 2022 07:23:57 -0700 (PDT) Date: Fri, 1 Jul 2022 16:22:40 +0200 In-Reply-To: <20220701142310.2188015-1-glider@google.com> Message-Id: <20220701142310.2188015-16-glider@google.com> Mime-Version: 1.0 References: <20220701142310.2188015-1-glider@google.com> X-Mailer: git-send-email 2.37.0.rc0.161.g10f37bed90-goog Subject: [PATCH v4 15/45] mm: kmsan: call KMSAN hooks from SLUB code From: Alexander Potapenko To: glider@google.com Cc: Alexander Viro , Alexei Starovoitov , 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 ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1656685438; a=rsa-sha256; cv=none; b=GxEgAcGAJTIJnS8LGT+rCKoi6DZdYskAbnSYfWrMH9hNCcsYopCcoFydpCwYrOuuITM0VP N+5GtXFskwzvikXtDsCTEIAuN+hWZzFgDPcqPGuBQwwAwW3gfm5DExyotKn2Bk9UqhfsZU 5eYIMn2tFVXP3QtX9vuwg9xP2eBTFQ4= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=ilZQasgN; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf19.hostedemail.com: domain of 3fQO_YgYKCJwCHE9ANCKKCHA.8KIHEJQT-IIGR68G.KNC@flex--glider.bounces.google.com designates 209.85.218.74 as permitted sender) smtp.mailfrom=3fQO_YgYKCJwCHE9ANCKKCHA.8KIHEJQT-IIGR68G.KNC@flex--glider.bounces.google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1656685438; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=yQ768gKjsg7o2qhom6fXRmA7hEqZpzUb/NLIF5UbCVk=; b=SYvCoBf32phth8quMHBl33Ux/CTY5jhXFaQ1bxPWJQabhka7GtpIFoeLO9tnIt/yJQH6r4 YYfB/aB9okRUrCMBAECOS6kmK1N+qNsHROd4JYRekGN76SN2kPsBrtXPS8XOBXSDCAKJ/t qtbK1qP9IFjfqfIhX1FX+IptslfULtc= X-Stat-Signature: ti61x34u1gtfzpf3jzrbn45nxw59rgsg X-Rspamd-Queue-Id: A97E71A0039 Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=ilZQasgN; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf19.hostedemail.com: domain of 3fQO_YgYKCJwCHE9ANCKKCHA.8KIHEJQT-IIGR68G.KNC@flex--glider.bounces.google.com designates 209.85.218.74 as permitted sender) smtp.mailfrom=3fQO_YgYKCJwCHE9ANCKKCHA.8KIHEJQT-IIGR68G.KNC@flex--glider.bounces.google.com X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1656685438-127425 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. In addition, we apply __no_kmsan_checks to get_freepointer_safe() to suppress reports when accessing freelist pointers that reside in freed objects. Signed-off-by: Alexander Potapenko Reviewed-by: Marco Elver --- v2: -- move the implementation of SLUB hooks here v4: -- change sizeof(type) to sizeof(*ptr) -- swap mm: and kmsan: in the subject -- get rid of kmsan_init(), replace it with __no_kmsan_checks 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 | 18 ++++++++++ 4 files changed, 156 insertions(+) diff --git a/include/linux/kmsan.h b/include/linux/kmsan.h index 699fe4f5b3bee..fd76cea338878 100644 --- a/include/linux/kmsan.h +++ b/include/linux/kmsan.h @@ -15,6 +15,7 @@ #include struct page; +struct kmem_cache; #ifdef CONFIG_KMSAN @@ -72,6 +73,44 @@ 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. @@ -138,6 +177,24 @@ 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 db9fb5c8dae73..d0de8195873d8 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -752,6 +752,7 @@ 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 b1281b8654bd3..b8b601f165087 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include #include @@ -359,6 +360,17 @@ 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, we apply __no_kmsan_checks to ensure that + * get_freepointer_safe() returns initialized memory. + */ +__no_kmsan_checks static inline void *get_freepointer_safe(struct kmem_cache *s, void *object) { unsigned long freepointer_addr; @@ -1709,6 +1721,7 @@ 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; } @@ -1716,12 +1729,14 @@ 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); @@ -3756,6 +3771,7 @@ 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); @@ -5939,6 +5955,7 @@ 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; } @@ -6040,6 +6057,7 @@ 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(*al)); return 0; }