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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1B54AC433F5 for ; Wed, 1 Jun 2022 12:29:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242485AbiFAM3G (ORCPT ); Wed, 1 Jun 2022 08:29:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237528AbiFAM26 (ORCPT ); Wed, 1 Jun 2022 08:28:58 -0400 Received: from mail-wr1-x42b.google.com (mail-wr1-x42b.google.com [IPv6:2a00:1450:4864:20::42b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 77BF97E1D3 for ; Wed, 1 Jun 2022 05:28:56 -0700 (PDT) Received: by mail-wr1-x42b.google.com with SMTP id u3so2148414wrg.3 for ; Wed, 01 Jun 2022 05:28:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=IelEAvxuftzpFUTjVmjDc8U27FXmxMCPT7XI/4vcyT8=; b=Xa5y6uuLTlRYUa8V+e+/4JGPqwWm2HXsZWjGZeeynhrY/Xmyj9Sygw8VjuP/t1qO07 b2+G7hy4jPbHYj4VR8+g6vNRSDiAMdMGrwakeY/Jt4oyrV/PIe9jYogIbXAChrQ1NX/q KXsVuA2nYTNvZ5hS+gagvPnv4SwP/A4pwD5iVVFUu6QJHdX5/k7C2a1KgXGwGds8f5JK OYOrIYqTFUmQF7dVZJDkxIqRh6wPMekV1sdfq2P8C7El1JNPpClVuKuDLuIDX/Iw4eOy SUxWIis9mGZjLv0zQTMoUkbN184rVl41TbSMBIS5Rt2lAWbYNJfVzMbeM1Q4aCD9ugYJ u/BQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=IelEAvxuftzpFUTjVmjDc8U27FXmxMCPT7XI/4vcyT8=; b=3kY8HMpRI6b1/z7LDv+055GaW4Plo49bgvzTVN4Ing+UEMz0wuU6R9FW3NG4E2eS+j mFz3mnUzgbNnDUlySW3pmTKhS2v7n/dYBacfqq7kKLBUR01yLI/tMbqk/6UsliLGW4Ey aoRopnqJ8zNgePxbinbXZjRelaToGP2VPzRmgeRxQF9bd1L97aGEM/GDAkP5QL2LGkMZ weI4BPuNo8Ph4d1OdKHRmbB5fkRVhgTTwXg9/AHNlfKfrf44WR5GRzJB8cm8vDcvXR0T PO5Jhy5N4kagFCzOl+W690QaGVafyRY8SGIkLJM7Xw0vrjycvhRi39vleiA2t5ozcWDU ViBg== X-Gm-Message-State: AOAM531BpNGKSJS86EFR/ls2IdVNXfk+tvfRLZuKGGH6lygolLLxplfF 2/GX29uhVDXUT+KxtD+hHEHC+g== X-Google-Smtp-Source: ABdhPJzTQYqHD3AuswM6IObr0zI5e+8BOvSIy4TzO8YrDCGcOJI2pM6bUMd9ayvHvb5scIj0s/xyUQ== X-Received: by 2002:a05:6000:16cb:b0:20e:63aa:7a31 with SMTP id h11-20020a05600016cb00b0020e63aa7a31mr54674152wrf.253.1654086534694; Wed, 01 Jun 2022 05:28:54 -0700 (PDT) Received: from elver.google.com ([2a00:79e0:9c:201:ed43:9390:62cb:50ee]) by smtp.gmail.com with ESMTPSA id l10-20020a5d410a000000b0020fc6590a12sm1447145wrp.41.2022.06.01.05.28.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Jun 2022 05:28:54 -0700 (PDT) Date: Wed, 1 Jun 2022 14:28:48 +0200 From: Marco Elver To: andrey.konovalov@linux.dev Cc: Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Andrey Ryabinin , kasan-dev@googlegroups.com, Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: Re: [PATCH 3/3] kasan: fix zeroing vmalloc memory with HW_TAGS Message-ID: References: <4c76a95aff79723de76df146a10888a5a9196faf.1654011120.git.andreyknvl@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/2.1.4 (2021-12-11) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 31, 2022 at 05:43PM +0200, andrey.konovalov@linux.dev wrote: > From: Andrey Konovalov > > HW_TAGS KASAN skips zeroing page_alloc allocations backing vmalloc > mappings via __GFP_SKIP_ZERO. Instead, these pages are zeroed via > kasan_unpoison_vmalloc() by passing the KASAN_VMALLOC_INIT flag. > > The problem is that __kasan_unpoison_vmalloc() does not zero pages > when either kasan_vmalloc_enabled() or is_vmalloc_or_module_addr() fail. > > Thus: > > 1. Change __vmalloc_node_range() to only set KASAN_VMALLOC_INIT when > __GFP_SKIP_ZERO is set. > > 2. Change __kasan_unpoison_vmalloc() to always zero pages when the > KASAN_VMALLOC_INIT flag is set. > > 3. Add WARN_ON() asserts to check that KASAN_VMALLOC_INIT cannot be set > in other early return paths of __kasan_unpoison_vmalloc(). > > Also clean up the comment in __kasan_unpoison_vmalloc. > > Fixes: 23689e91fb22 ("kasan, vmalloc: add vmalloc tagging for HW_TAGS") > Signed-off-by: Andrey Konovalov > --- > mm/kasan/hw_tags.c | 30 ++++++++++++++++++++++-------- > mm/vmalloc.c | 10 +++++----- > 2 files changed, 27 insertions(+), 13 deletions(-) > > diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c > index 9e1b6544bfa8..c0ec01eadf20 100644 > --- a/mm/kasan/hw_tags.c > +++ b/mm/kasan/hw_tags.c > @@ -263,21 +263,31 @@ void *__kasan_unpoison_vmalloc(const void *start, unsigned long size, > u8 tag; > unsigned long redzone_start, redzone_size; > > - if (!kasan_vmalloc_enabled()) > - return (void *)start; > + if (!kasan_vmalloc_enabled() || !is_vmalloc_or_module_addr(start)) { > + struct page *page; > + const void *addr; > + > + /* Initialize memory if required. */ > + This whole block of code looks out-of-place in this function, since it's not at all related to unpoisoning but a fallback if KASAN-vmalloc is off but we still want to initialize the memory. Maybe to ease readability here I'd change it to look like: diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c index 11f661a2494b..227c20d09258 100644 --- a/mm/kasan/hw_tags.c +++ b/mm/kasan/hw_tags.c @@ -257,6 +257,21 @@ static void unpoison_vmalloc_pages(const void *addr, u8 tag) } } +/* + * Explicit initialization of pages if KASAN does not handle VM_ALLOC + * allocations. + */ +static void init_vmalloc_pages_explicit(const void *start, unsigned long size) +{ + const void *addr; + + for (addr = start; addr < start + size; addr += PAGE_SIZE) { + struct page *page = virt_to_page(addr); + + clear_highpage_kasan_tagged(page); + } +} + void *__kasan_unpoison_vmalloc(const void *start, unsigned long size, kasan_vmalloc_flags_t flags) { @@ -264,19 +279,8 @@ void *__kasan_unpoison_vmalloc(const void *start, unsigned long size, unsigned long redzone_start, redzone_size; if (!kasan_vmalloc_enabled() || !is_vmalloc_or_module_addr(start)) { - struct page *page; - const void *addr; - - /* Initialize memory if required. */ - - if (!(flags & KASAN_VMALLOC_INIT)) - return (void *)start; - - for (addr = start; addr < start + size; addr += PAGE_SIZE) { - page = virt_to_page(addr); - clear_highpage_kasan_tagged(page); - } - + if (flags & KASAN_VMALLOC_INIT) + init_vmalloc_pages_explicit(start, size); return (void *)start; }