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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 900FCC433F5 for ; Wed, 1 Jun 2022 12:28:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 213898D0014; Wed, 1 Jun 2022 08:28:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1C2258D000E; Wed, 1 Jun 2022 08:28:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 088CD8D0014; Wed, 1 Jun 2022 08:28:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id EC8DB8D000E for ; Wed, 1 Jun 2022 08:28:56 -0400 (EDT) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id B7087349CC for ; Wed, 1 Jun 2022 12:28:56 +0000 (UTC) X-FDA: 79529596272.25.C8989E6 Received: from mail-wr1-f54.google.com (mail-wr1-f54.google.com [209.85.221.54]) by imf10.hostedemail.com (Postfix) with ESMTP id 78AF2C005F for ; Wed, 1 Jun 2022 12:28:12 +0000 (UTC) Received: by mail-wr1-f54.google.com with SMTP id d26so2113705wrb.13 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=FvENSUwAJxa9KGQmhUdbZjB8gamDicbk4LQ54RM5uvgmdXillTZ5zfcz8Uq5lxRdZU AO+Y8UIlLyEbnvbOauUHBgpL6sBavKA+oOs/RWlLlkVPJQ+BHzudBGAvYyUz0zQsP++K dHvqcpN4cYBIehdIoeSp7CE8G+LLfOT2T2h/Om8MfuQ5ANnhLsTf/JrDmKq2uPEzZn1M EzD6brxpJ7OEFY+aYCu1IB0dpIBAR4SZlu/zoFC1ubUf8Olh2MmtiL2n5odEJh88pNCn 1D5i33rkHAqAk/P42CD2/bw2Cnc6xg740F90krKN26b7gcHDLx+mxgHYBtiymS1kwGUv s+OA== X-Gm-Message-State: AOAM531yNY54S/pN2WzgWFiPTXZFL45tHyjw59EslllB3ogHh0ia4K4R IFf+ICuCzx9pr05xFUwX1nZYWw== 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) X-Rspamd-Queue-Id: 78AF2C005F X-Stat-Signature: fg4jaexrrj4st8ab6y9qcimha1h5pmp1 X-Rspam-User: Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=Xa5y6uuL; spf=pass (imf10.hostedemail.com: domain of elver@google.com designates 209.85.221.54 as permitted sender) smtp.mailfrom=elver@google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspamd-Server: rspam08 X-HE-Tag: 1654086492-260686 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: 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; }