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 175E8C54FD0 for ; Thu, 23 Apr 2020 19:16:11 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C393A20661 for ; Thu, 23 Apr 2020 19:16:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="PrVhQate" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C393A20661 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 6D72A8E0008; Thu, 23 Apr 2020 15:16:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6AC908E0003; Thu, 23 Apr 2020 15:16:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5C31C8E0008; Thu, 23 Apr 2020 15:16:10 -0400 (EDT) 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 407868E0003 for ; Thu, 23 Apr 2020 15:16:10 -0400 (EDT) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 034538248047 for ; Thu, 23 Apr 2020 19:16:10 +0000 (UTC) X-FDA: 76740075300.26.pen76_35c9f222a8915 X-HE-Tag: pen76_35c9f222a8915 X-Filterd-Recvd-Size: 6870 Received: from mail-pg1-f195.google.com (mail-pg1-f195.google.com [209.85.215.195]) by imf08.hostedemail.com (Postfix) with ESMTP for ; Thu, 23 Apr 2020 19:16:09 +0000 (UTC) Received: by mail-pg1-f195.google.com with SMTP id t11so3373375pgg.2 for ; Thu, 23 Apr 2020 12:16:09 -0700 (PDT) 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=6TU92epbaNZsIRFLIrtkwVMXMujeFqPQ0Hu/lYjV73w=; b=PrVhQatey9f/O6DPSYW9m/XL6w4puh/sl+n84G0mZow/XTeEZSKhYYS9sI5vNWR04q VX9zySOc775jATDnh8wJZj0AtILJNav7Xf5a9SRZQLrzV/+LfnI8z+oZ1Yl/yVwyXA2Q +wuD+rpU4vHm6aSC6QnC3OCtv8SSFiG/Hk3dLXpYkrYD5n2C3QFAweL5bfHyvoIC55qy 124pW0MHKJnHhqdhukjJ1eo0aOWoVhZWlLcGZAW6kTDQz4ebZBB1VVNk/7AGSGGgV5V0 PBWB54kXZ4fe2zaglZNa4T3SlVJUs7G/2fbz2TV31vYaRh9+NDSRaABf2cPISqzZLQEg ySxw== 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=6TU92epbaNZsIRFLIrtkwVMXMujeFqPQ0Hu/lYjV73w=; b=scI5/K46kJ2yduc+oOch+4p+hsW96E7lA1dtYiJBRqoyasfX+TfnxITQuq1jixsYo4 A/6/Lc2foj0euAruBaCxzl5Z7R4b+wHRBNw4KJlmce59/SAoRiqAgIjWdRC7XHOlFFBP cmNs7QZvyh07NgRCEUVXKv+rl4dPTx26X5FLiqWfaac2ahGAr0fxIkEg/6n+UXX8lNRO sNnZXQaEAOZNCBy9hj2wIZ3o7vUGlyN5fGHb2alVvJnoTTXL1jz7g8ivLHT9n603+Nh6 sQtmHlX0SjfrMtCA9fGg9swm7G9cT6o7k7Ca/jh+dcgwSf7s1aJzJeoQ7qGTF9r/E6m3 +EJg== X-Gm-Message-State: AGi0PuaBo/t+vDL8I6pbobYmOpvf5z0qbdjzX0Jct4pfgiKv3AMOy60X aT43k7NJSRPvaghTjjZAH+WZ5xtiVksxbYQSxH98aA== X-Google-Smtp-Source: APiQypK1A9jz48VrzinPbKdzCiVoCy8on7kQ9LsOB3k/GO2IqbKvGwufNLKRzSsd7kzIZJ3N+ckrGvvFH2FlZ5tEArI= X-Received: by 2002:a62:5289:: with SMTP id g131mr5553143pfb.318.1587669368488; Thu, 23 Apr 2020 12:16:08 -0700 (PDT) MIME-Version: 1.0 References: <20200325161249.55095-1-glider@google.com> <20200325161249.55095-12-glider@google.com> In-Reply-To: <20200325161249.55095-12-glider@google.com> From: Andrey Konovalov Date: Thu, 23 Apr 2020 21:15:57 +0200 Message-ID: Subject: Re: [PATCH v5 11/38] kmsan: make READ_ONCE_TASK_STACK() return initialized values To: Alexander Potapenko Cc: Vegard Nossum , Dmitry Vyukov , Marco Elver , Linux Memory Management List , Alexander Viro , Andreas Dilger , Andrew Morton , 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 Hocko , 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 Wed, Mar 25, 2020 at 5:13 PM 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: Marco Elver > Cc: Andrey Konovalov > Cc: linux-mm@kvack.org > Acked-by: Marco Elver Reviewed-by: Andrey Konovalov > > --- > v4: > - added an #include as requested by Marco Elver > > Change-Id: Ie73e5a41fdc8195699928e65f5cbe0d3d3c9e2fa > --- > arch/x86/include/asm/unwind.h | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h > index 499578f7e6d7b..82c3bceb9999c 100644 > --- a/arch/x86/include/asm/unwind.h > +++ b/arch/x86/include/asm/unwind.h > @@ -4,6 +4,7 @@ > > #include > #include > +#include > #include > #include > > @@ -100,9 +101,10 @@ 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 +113,7 @@ 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) > -- > 2.25.1.696.g5e7596f4ac-goog >