From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-20.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE051C2D0A3 for ; Wed, 4 Nov 2020 23:20:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 53C8220786 for ; Wed, 4 Nov 2020 23:20:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="urLNJdGS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732928AbgKDXUt (ORCPT ); Wed, 4 Nov 2020 18:20:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44286 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732544AbgKDXUq (ORCPT ); Wed, 4 Nov 2020 18:20:46 -0500 Received: from mail-wr1-x449.google.com (mail-wr1-x449.google.com [IPv6:2a00:1450:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4CF25C0613CF for ; Wed, 4 Nov 2020 15:20:44 -0800 (PST) Received: by mail-wr1-x449.google.com with SMTP id x16so46868wrg.7 for ; Wed, 04 Nov 2020 15:20:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=C6Op3yFR6sxPD/1lbh7YRsoWm4fdKowdqrD7aVgHz7A=; b=urLNJdGSUOup2QSd3Xo8K2IAxTAD4dxietwPBoyckjUmP4CteZp8rLtUmfDhg7cqaT 91sVwygPNWlNpkUAJoiivg0+QvRZj3TO8Wrb43cjTxERiNpdAb6ci817hmSubqgKl2Bc fxz1aVjxfud/M3zsEs5/BB+wXnyQHv/Ruo3fJs8Qt7G7php2kpi2YJ1Mv0INw+MHmxXE f/ledyhbcHTBWQXxDowUv1LwE8WIOV6XZJJWgBqbhXSrSTrhCmCfA5ElEAkkJZ28NcjT ll6raxQ/OcE+COdlYmOKrspK1fuZLqm8V8wFf4pp4SZfZtX3NGRlu4pkxUqMVi4nvgcP y9tA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=C6Op3yFR6sxPD/1lbh7YRsoWm4fdKowdqrD7aVgHz7A=; b=Ft5ywLkJGzXLY5MrtCsLhVb40vybaIbzN3ytOAMsX/MceKhgIseUwR0fOkM6jEzX08 VbaIuhdJ/ZBjNw8UsoQ1ZRxu/YbPgx/YZuJH7BVL/v6XgvqkJniuLHqvy4xq+WXbGQjI YBoakk8igdEePcv6LNry113JsyoY1/szftQ3sHxF7mKhASeV8gbep9rmYzHcN6aoNfOh 6OPeStC9d2mDJTcOZkOtfD+tqeFF5LMTRBs2XHi9l1J39rK7BiZ9XXTAzkyoty/Y06Cb TtDK/ttdkO1sI2fBzvkJXkWmaDQBMQtQB/xLf+sieNsgtNm/JQKYn/TVDHg20okCHGVw yTAg== X-Gm-Message-State: AOAM531cHj5rj3vjQ/9dHjcCvsU/RFqwr9cucRmY3dJDNE5TzyZkINX4 XMDhNGvHLDVJNKtryzcGsoalx5i8orYkQR5D X-Google-Smtp-Source: ABdhPJzBnouBFsSKxvskBclzmPBIxPEASCVKLTTX8D2WfoMu1h7X9WE1X4orLp0LUTH+zZibNJ/ozADkRrawKBgj Sender: "andreyknvl via sendgmr" X-Received: from andreyknvl3.muc.corp.google.com ([2a00:79e0:15:13:7220:84ff:fe09:7e9d]) (user=andreyknvl job=sendgmr) by 2002:a1c:2487:: with SMTP id k129mr97091wmk.86.1604532042965; Wed, 04 Nov 2020 15:20:42 -0800 (PST) Date: Thu, 5 Nov 2020 00:18:55 +0100 In-Reply-To: Message-Id: <578dd0990cc6a02fd47d2d0a442db1c628fef91e.1604531793.git.andreyknvl@google.com> Mime-Version: 1.0 References: X-Mailer: git-send-email 2.29.1.341.ge80a0c044ae-goog Subject: [PATCH v8 40/43] kasan, mm: reset tags when accessing metadata From: Andrey Konovalov To: Catalin Marinas Cc: Will Deacon , Vincenzo Frascino , Dmitry Vyukov , Andrey Ryabinin , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , Andrew Morton , kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Kernel allocator code accesses metadata for slab objects, that may lie out-of-bounds of the object itself, or be accessed when an object is freed. Such accesses trigger tag faults and lead to false-positive reports with hardware tag-based KASAN. Software KASAN modes disable instrumentation for allocator code via KASAN_SANITIZE Makefile macro, and rely on kasan_enable/disable_current() annotations which are used to ignore KASAN reports. With hardware tag-based KASAN neither of those options are available, as it doesn't use compiler instrumetation, no tag faults are ignored, and MTE is disabled after the first one. Instead, reset tags when accessing metadata (currently only for SLUB). Signed-off-by: Andrey Konovalov Signed-off-by: Vincenzo Frascino Acked-by: Marco Elver --- Change-Id: I39f3c4d4f29299d4fbbda039bedf230db1c746fb --- mm/page_alloc.c | 4 +++- mm/page_poison.c | 2 +- mm/slub.c | 29 ++++++++++++++++------------- 3 files changed, 20 insertions(+), 15 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 23f5066bd4a5..6231a6e456cf 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1195,8 +1195,10 @@ static void kernel_init_free_pages(struct page *page, int numpages) /* s390's use of memset() could override KASAN redzones. */ kasan_disable_current(); - for (i = 0; i < numpages; i++) + for (i = 0; i < numpages; i++) { + page_kasan_tag_reset(page + i); clear_highpage(page + i); + } kasan_enable_current(); } diff --git a/mm/page_poison.c b/mm/page_poison.c index ae0482cded87..e6c994af7518 100644 --- a/mm/page_poison.c +++ b/mm/page_poison.c @@ -53,7 +53,7 @@ static void poison_page(struct page *page) /* KASAN still think the page is in-use, so skip it. */ kasan_disable_current(); - memset(addr, PAGE_POISON, PAGE_SIZE); + memset(kasan_reset_tag(addr), PAGE_POISON, PAGE_SIZE); kasan_enable_current(); kunmap_atomic(addr); } diff --git a/mm/slub.c b/mm/slub.c index b30be2385d1c..df2fd5b57df1 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -249,7 +249,7 @@ static inline void *freelist_ptr(const struct kmem_cache *s, void *ptr, { #ifdef CONFIG_SLAB_FREELIST_HARDENED /* - * When CONFIG_KASAN_SW_TAGS is enabled, ptr_addr might be tagged. + * When CONFIG_KASAN_SW/HW_TAGS is enabled, ptr_addr might be tagged. * Normally, this doesn't cause any issues, as both set_freepointer() * and get_freepointer() are called with a pointer with the same tag. * However, there are some issues with CONFIG_SLUB_DEBUG code. For @@ -275,6 +275,7 @@ static inline void *freelist_dereference(const struct kmem_cache *s, static inline void *get_freepointer(struct kmem_cache *s, void *object) { + object = kasan_reset_tag(object); return freelist_dereference(s, object + s->offset); } @@ -304,6 +305,7 @@ static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp) BUG_ON(object == fp); /* naive detection of double free or corruption */ #endif + freeptr_addr = (unsigned long)kasan_reset_tag((void *)freeptr_addr); *(void **)freeptr_addr = freelist_ptr(s, fp, freeptr_addr); } @@ -538,8 +540,8 @@ static void print_section(char *level, char *text, u8 *addr, unsigned int length) { metadata_access_enable(); - print_hex_dump(level, text, DUMP_PREFIX_ADDRESS, 16, 1, addr, - length, 1); + print_hex_dump(level, kasan_reset_tag(text), DUMP_PREFIX_ADDRESS, + 16, 1, addr, length, 1); metadata_access_disable(); } @@ -570,7 +572,7 @@ static struct track *get_track(struct kmem_cache *s, void *object, p = object + get_info_end(s); - return p + alloc; + return kasan_reset_tag(p + alloc); } static void set_track(struct kmem_cache *s, void *object, @@ -583,7 +585,8 @@ static void set_track(struct kmem_cache *s, void *object, unsigned int nr_entries; metadata_access_enable(); - nr_entries = stack_trace_save(p->addrs, TRACK_ADDRS_COUNT, 3); + nr_entries = stack_trace_save(kasan_reset_tag(p->addrs), + TRACK_ADDRS_COUNT, 3); metadata_access_disable(); if (nr_entries < TRACK_ADDRS_COUNT) @@ -747,7 +750,7 @@ static __printf(3, 4) void slab_err(struct kmem_cache *s, struct page *page, static void init_object(struct kmem_cache *s, void *object, u8 val) { - u8 *p = object; + u8 *p = kasan_reset_tag(object); if (s->flags & SLAB_RED_ZONE) memset(p - s->red_left_pad, val, s->red_left_pad); @@ -777,7 +780,7 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page, u8 *addr = page_address(page); metadata_access_enable(); - fault = memchr_inv(start, value, bytes); + fault = memchr_inv(kasan_reset_tag(start), value, bytes); metadata_access_disable(); if (!fault) return 1; @@ -873,7 +876,7 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page) pad = end - remainder; metadata_access_enable(); - fault = memchr_inv(pad, POISON_INUSE, remainder); + fault = memchr_inv(kasan_reset_tag(pad), POISON_INUSE, remainder); metadata_access_disable(); if (!fault) return 1; @@ -1118,7 +1121,7 @@ void setup_page_debug(struct kmem_cache *s, struct page *page, void *addr) return; metadata_access_enable(); - memset(addr, POISON_INUSE, page_size(page)); + memset(kasan_reset_tag(addr), POISON_INUSE, page_size(page)); metadata_access_disable(); } @@ -1566,10 +1569,10 @@ static inline bool slab_free_freelist_hook(struct kmem_cache *s, * Clear the object and the metadata, but don't touch * the redzone. */ - memset(object, 0, s->object_size); + memset(kasan_reset_tag(object), 0, s->object_size); rsize = (s->flags & SLAB_RED_ZONE) ? s->red_left_pad : 0; - memset((char *)object + s->inuse, 0, + memset((char *)kasan_reset_tag(object) + s->inuse, 0, s->size - s->inuse - rsize); } @@ -2883,10 +2886,10 @@ static __always_inline void *slab_alloc_node(struct kmem_cache *s, stat(s, ALLOC_FASTPATH); } - maybe_wipe_obj_freeptr(s, object); + maybe_wipe_obj_freeptr(s, kasan_reset_tag(object)); if (unlikely(slab_want_init_on_alloc(gfpflags, s)) && object) - memset(object, 0, s->object_size); + memset(kasan_reset_tag(object), 0, s->object_size); slab_post_alloc_hook(s, objcg, gfpflags, 1, &object); -- 2.29.1.341.ge80a0c044ae-goog