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=-14.4 required=3.0 tests=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,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 CCEE5C432C0 for ; Mon, 2 Dec 2019 10:08:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 795292070B for ; Mon, 2 Dec 2019 10:08:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="JzfRhG3w" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 795292070B Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EF3DD6B0003; Mon, 2 Dec 2019 05:08:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EA4DC6B0006; Mon, 2 Dec 2019 05:08:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D6DDE6B0007; Mon, 2 Dec 2019 05:08:11 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0202.hostedemail.com [216.40.44.202]) by kanga.kvack.org (Postfix) with ESMTP id BE5F36B0003 for ; Mon, 2 Dec 2019 05:08:11 -0500 (EST) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 68F6E1CBE for ; Mon, 2 Dec 2019 10:08:11 +0000 (UTC) X-FDA: 76219775982.10.debt27_2a579f0955309 X-HE-Tag: debt27_2a579f0955309 X-Filterd-Recvd-Size: 6511 Received: from mail-oi1-f194.google.com (mail-oi1-f194.google.com [209.85.167.194]) by imf45.hostedemail.com (Postfix) with ESMTP for ; Mon, 2 Dec 2019 10:08:10 +0000 (UTC) Received: by mail-oi1-f194.google.com with SMTP id l20so31869364oie.10 for ; Mon, 02 Dec 2019 02:08:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=lcN6VoMf/op2be4U+YT6njJm6Ejx8YlM5NET2IB2PU0=; b=JzfRhG3wO+vkVhIwqlt4UfLeJzIR8ReJga7NBds9DSiQh9HUhbyaor2n707PmFnwPs 8GAoA0QGc2+Dp42mjKlrxlHXdOfIEBK/g91L8eWnMhvLH/20E7c6gsUyVBMYD50fnZ1q Alznyz6kWU3J8TOhqysWfr8FodlEKxhTC9ukBvWJzbQ7sTgaPtaO64kJJhMlSrbjUxc5 XLlHC2H4BYZef2aHCI+IyKwxxoi53dhlxZ273Tr4GfI4KKXBIZAj1RTVc9+yKwPNpscC HjxkWn/Zus5X3V6tAH8na3KV2SBcsyE+i1xjGsJoXZAldrnSgcP199ZNw3jrt3MN0Y2b G4HQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=lcN6VoMf/op2be4U+YT6njJm6Ejx8YlM5NET2IB2PU0=; b=DbbkTVfHsumgGtuVX12lc+pXH4tGcooj98xLyL+AXOp1dXesEZ6Mg05iRHBcN5krgK KbpiDCah7P4/rMaWw48Ei5JXXw9m1jo5gShNyOGEiEvFogmkPjQkAecjYObYArRs5aL7 HjA0yXPGnyOosiqWkdzjgj2sVvG1VvOiN31EB8ZSBzQ/jOTb/frcfe798dHwX397alqB TiOiagoZ9eMmWDOruNgCRzUpMmdBBC7ZZTFQftrC4iWdQBgsl43j7Id21SYyEmAY7mQ9 F8QamHlKsaTOlA9i7UygF0SmSqyjnjOa316PeMK+pUGTFw2WuA6d0RM1q73KYLCNo87Z iPSQ== X-Gm-Message-State: APjAAAU10wCHp1Sgs4Ca/mSONiv+9QHlin8NOcnBp64Ul7pcCD9BEaLt 5hODeIc9LCAWQ28Ckc96RRDurx1lEDaj3CR7HggZhQ== X-Google-Smtp-Source: APXvYqxDCRRdAsI3p+pUJz+dEvhkeq3ZliLbZ64lR7uvU95RbhObrHO7fc//0ozJd56wDRdEcC/nhp048yaEVZd3NJA= X-Received: by 2002:aca:d4c1:: with SMTP id l184mr23330084oig.172.1575281289794; Mon, 02 Dec 2019 02:08:09 -0800 (PST) MIME-Version: 1.0 References: <20191122112621.204798-1-glider@google.com> <20191122112621.204798-14-glider@google.com> In-Reply-To: <20191122112621.204798-14-glider@google.com> From: Marco Elver Date: Mon, 2 Dec 2019 11:07:58 +0100 Message-ID: Subject: Re: [PATCH RFC v3 13/36] kmsan: make READ_ONCE_TASK_STACK() return initialized values To: Alexander Potapenko Cc: Vegard Nossum , Dmitry Vyukov , Linux Memory Management List , Al Viro , Andreas Dilger , Andrew Morton , Andrey Konovalov , Andrey Ryabinin , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Christoph Hellwig , Christoph Hellwig , "Darrick J. Wong" , "David S. Miller" , Dmitry Torokhov , Eric Biggers , Eric Dumazet , Eric Van Hensbergen , Greg Kroah-Hartman , Harry Wentland , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jason Wang , Jens Axboe , Marek Szyprowski , Mark Rutland , "Martin K. Petersen" , Martin Schwidefsky , Matthew Wilcox , "Michael S. Tsirkin" , Michal Simek , Petr Mladek , Qian Cai , Randy Dunlap , Robin Murphy , Sergey Senozhatsky , Steven Rostedt , Takashi Iwai , "Theodore Ts'o" , Thomas Gleixner , Vasily Gorbik , Wolfram Sang Content-Type: text/plain; charset="UTF-8" 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 Fri, 22 Nov 2019 at 12:27, wrote: > > To avoid false positives, assume that reading from the task stack > always produces initialized values. > > Signed-off-by: Alexander Potapenko > To: Alexander Potapenko > Cc: Vegard Nossum > Cc: Dmitry Vyukov > Cc: linux-mm@kvack.org Acked-by: Marco Elver assuming previous patch's include for kmsan-checks.h is added. > --- > > Change-Id: Ie73e5a41fdc8195699928e65f5cbe0d3d3c9e2fa > --- > arch/x86/include/asm/unwind.h | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h > index 499578f7e6d7..f60c2bd1ddf2 100644 > --- a/arch/x86/include/asm/unwind.h > +++ b/arch/x86/include/asm/unwind.h > @@ -100,9 +100,10 @@ void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size, > #endif > > /* > - * This disables KASAN checking when reading a value from another task's stack, > - * since the other task could be running on another CPU and could have poisoned > - * the stack in the meantime. > + * This disables KASAN/KMSAN checking when reading a value from another task's > + * stack, since the other task could be running on another CPU and could have > + * poisoned the stack in the meantime. Frame pointers are uninitialized by > + * default, so for KMSAN we mark the return value initialized unconditionally. > */ > #define READ_ONCE_TASK_STACK(task, x) \ > ({ \ > @@ -111,7 +112,7 @@ void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size, > val = READ_ONCE(x); \ > else \ > val = READ_ONCE_NOCHECK(x); \ > - val; \ > + KMSAN_INIT_VALUE(val); \ > }) > > static inline bool task_on_another_cpu(struct task_struct *task) > -- > 2.24.0.432.g9d3f5f5b63-goog >