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 84F74C43603 for ; Thu, 5 Dec 2019 15:52:17 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 42D5B206DB for ; Thu, 5 Dec 2019 15:52:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="faUJxqQ2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 42D5B206DB 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 C43286B10F3; Thu, 5 Dec 2019 10:52:16 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BCCEC6B10F4; Thu, 5 Dec 2019 10:52:16 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A95016B10F5; Thu, 5 Dec 2019 10:52:16 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0227.hostedemail.com [216.40.44.227]) by kanga.kvack.org (Postfix) with ESMTP id 8C6CE6B10F3 for ; Thu, 5 Dec 2019 10:52:16 -0500 (EST) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 4648252BF for ; Thu, 5 Dec 2019 15:52:16 +0000 (UTC) X-FDA: 76231529472.04.pest97_13b62b55cd61a X-HE-Tag: pest97_13b62b55cd61a X-Filterd-Recvd-Size: 7217 Received: from mail-wm1-f68.google.com (mail-wm1-f68.google.com [209.85.128.68]) by imf50.hostedemail.com (Postfix) with ESMTP for ; Thu, 5 Dec 2019 15:52:15 +0000 (UTC) Received: by mail-wm1-f68.google.com with SMTP id b11so4393088wmj.4 for ; Thu, 05 Dec 2019 07:52:15 -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:content-transfer-encoding; bh=tj1aenVNU3yWV7alzl4XLJxSXAtwQqRGFupb0rSIZq8=; b=faUJxqQ2j9iCvsmY6fEXHAlxXyoFDOXtjrrDfNkQnFo3RxEhSTkwsKgCtWi4kNi9BZ 3C1FY5ZMh2ghxW+Hc8sAFGm+4a40Jm3UEV5hEdXLBy/P3j2/sCBykXT2g5qr3d39RiME Ie01wGKB5cVuWIUaH8gEPcY272B8SYQSkiMM/7R0eaN/vEcbLHO5lu0NFein8PjYCmbO rMrwh3lEIh+hV8taNtSoFCUtJMexNUqem/jW8+MW/gVCgGZSBFX9QTDvbGLjp3WXKq1K k1EKj5vWVOMxRVyXGDHMWDiNUpRiZ7Q6NMq02u5mJUtxIFdQ7YbOJ758jie76prGP/Q+ Y7yg== 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:content-transfer-encoding; bh=tj1aenVNU3yWV7alzl4XLJxSXAtwQqRGFupb0rSIZq8=; b=prNGfSCCNmVdk/3isEhme6Cgmd3jkDFHzM7CzwvAL86lei4wc/LlBxqM1Vs/dVVqcZ TI/O5he8PEPfx0/GcIf4oM+iF2bOH6mEo5K8pUTSIfz24LZ9uoEWAfLn7rUfoQSEgT8s hgGeolpmlTCLosfg5ytx7PUIjBAQDt6CdpqaKPQmrckoEX0ch9RkU+I+CQd860cthTgZ 4pNuoM1c7+6oqv93ky4JqTSFsHJy80RLfygbfUYOY7lRz7FRow9/wTiQ9WID6p7bDLqj asYe5R6SUFSO/BpxwVMZOiSSeZh9A7a02LDw+AoUZ7Lp+KjaZq+UBHu/JxFxb3Du3qrD dy/w== X-Gm-Message-State: APjAAAWxh9UNSgtGkQ7GpgT3u/P4yu22ZrcLwwIMSInNpi2x7ETgYE8l RBmR/R3LYOvysNX5AMfeiHlIKl9pry4gVRKEHR5Gaw== X-Google-Smtp-Source: APXvYqzh3KIZyBVLoiq7LEqsblXGSkvnDEBtjuwmWF6P10mce/urx4WgVzkkKN2LGwOri7LXci8y7qum6bBv+Rc9qEQ= X-Received: by 2002:a7b:c632:: with SMTP id p18mr5693313wmk.175.1575561133810; Thu, 05 Dec 2019 07:52:13 -0800 (PST) MIME-Version: 1.0 References: <20191122112621.204798-1-glider@google.com> <20191122112621.204798-14-glider@google.com> In-Reply-To: From: Alexander Potapenko Date: Thu, 5 Dec 2019 16:52:02 +0100 Message-ID: Subject: Re: [PATCH RFC v3 13/36] kmsan: make READ_ONCE_TASK_STACK() return initialized values To: Marco Elver 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" Content-Transfer-Encoding: quoted-printable 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 Mon, Dec 2, 2019 at 11:08 AM Marco Elver wrote: > > 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. Yes, I'll add that include here as well in v4. > > --- > > > > 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/unwin= d.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 anothe= r task's > > + * stack, since the other task could be running on another CPU and cou= ld have > > + * poisoned the stack in the meantime. Frame pointers are uninitialize= d by > > + * default, so for KMSAN we mark the return value initialized uncondit= ionally. > > */ > > #define READ_ONCE_TASK_STACK(task, x) \ > > ({ \ > > @@ -111,7 +112,7 @@ void unwind_module_init(struct module *mod, void *o= rc_ip, size_t orc_ip_size, > > val =3D READ_ONCE(x); \ > > else \ > > val =3D 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 > > --=20 Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Stra=C3=9Fe, 33 80636 M=C3=BCnchen Gesch=C3=A4ftsf=C3=BChrer: Paul Manicle, Halimah DeLaine Prado Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg