From patchwork Tue Dec 14 16:20:30 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Potapenko X-Patchwork-Id: 12676381 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 00D9BC433F5 for ; Tue, 14 Dec 2021 16:34:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B3DC16B009A; Tue, 14 Dec 2021 11:23:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id AEBFD6B009B; Tue, 14 Dec 2021 11:23:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 98D156B009C; Tue, 14 Dec 2021 11:23:08 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0247.hostedemail.com [216.40.44.247]) by kanga.kvack.org (Postfix) with ESMTP id 896F26B009A for ; Tue, 14 Dec 2021 11:23:08 -0500 (EST) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 509F9180DA19C for ; Tue, 14 Dec 2021 16:22:58 +0000 (UTC) X-FDA: 78916918836.21.593505B Received: from mail-wr1-f74.google.com (mail-wr1-f74.google.com [209.85.221.74]) by imf12.hostedemail.com (Postfix) with ESMTP id 738254000D for ; Tue, 14 Dec 2021 16:22:52 +0000 (UTC) Received: by mail-wr1-f74.google.com with SMTP id q17-20020adfcd91000000b0017bcb12ad4fso4850892wrj.12 for ; Tue, 14 Dec 2021 08:22:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=RahC8+o5lwzgAvVh7zx+7oLLYsmuRte28muTwb6Tt+E=; b=kXx7p+TaPFKll9TwTsjKqgOr+UNTl28fMuejIwJkUW6waRnU3wWq6CRAGRiOmMac5D gTwgJsYAX2xUIUEmYzvGp2hyPCP4Wm56BgSaKglv8p253lIAFKtOY7B1DPzLwsEBSgO3 v8bHgT4qtyZDjeAG+BxPNiXz6Qdhn2gdCfTrLJNeLq51/HcT+lJ2Ymj5ZoFxtQHe6oAH IP/iLEHWxBPgmzVXkPVim068SXK6M2LIzTb5O32c/PJFtTHPYZt4cKS+VoyYpNtZVNo1 ucPlb5/R1XeuTBxqsz+siScqUDO0GJ60AvXx4VJ4v0JlBp6aMTl7d0fSj2nEnuPbOiBY xwFg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=RahC8+o5lwzgAvVh7zx+7oLLYsmuRte28muTwb6Tt+E=; b=JHynhPwc5ClldTe8oH1O424ANe3aaWMANRmUejMYb1qdTl3lc2BFX4QX8d2TBSo50T gzbaspOjyCot2t5k4mHSfpoJI3EVyCzwEUsT9bk6g33NDHhVHMuNEa3jE8YMPkjmhT1N KrY98rIOpNywqlBk2t+ueEYXOVOXbElMw5+swhtmEPTWS6h1K2KDHjfKxk8LBjR2Kjw0 wXoZOtbclwenROsxjtspzHs5EqEmt4Ig1zXPu+T2egDNHSzRBSaZFzDENj1foLWVsLIU Tu83CFIw2AfldaErF8bzhguhpKKIjOpTMhDKjLVrKShe4iba/gTgy0G3p+hs5UOUT556 ZKMw== X-Gm-Message-State: AOAM532iDQP35BpR+sFZ0flvAJWN2UJZzocU475K541WWSw56G8yO43H I05X67n1oHe2vIb13B86znP0Tadoqls= X-Google-Smtp-Source: ABdhPJyS0Vu024wH2nH284+5iPoP3BAzIuLrJ7O37SST95Qm9Dj5aepJ2oaLYM+pIKc9+sfuQR2fDWvghJc= X-Received: from glider.muc.corp.google.com ([2a00:79e0:15:13:357e:2b9d:5b13:a652]) (user=glider job=sendgmr) by 2002:a7b:c097:: with SMTP id r23mr46571900wmh.193.1639498976421; Tue, 14 Dec 2021 08:22:56 -0800 (PST) Date: Tue, 14 Dec 2021 17:20:30 +0100 In-Reply-To: <20211214162050.660953-1-glider@google.com> Message-Id: <20211214162050.660953-24-glider@google.com> Mime-Version: 1.0 References: <20211214162050.660953-1-glider@google.com> X-Mailer: git-send-email 2.34.1.173.g76aa8bc2d0-goog Subject: [PATCH 23/43] kmsan: make READ_ONCE_TASK_STACK() return initialized values From: Alexander Potapenko To: glider@google.com Cc: Alexander Viro , Andrew Morton , Andrey Konovalov , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Borislav Petkov , Christoph Hellwig , Christoph Lameter , David Rientjes , Dmitry Vyukov , Eric Dumazet , Greg Kroah-Hartman , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jens Axboe , Joonsoo Kim , Kees Cook , Marco Elver , Matthew Wilcox , "Michael S. Tsirkin" , Pekka Enberg , Peter Zijlstra , Petr Mladek , Steven Rostedt , Thomas Gleixner , Vasily Gorbik , Vegard Nossum , Vlastimil Babka , linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 738254000D X-Stat-Signature: 1f5btdz8pttyrrc8zpqz1t1bc8byxmqq Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=kXx7p+Ta; spf=pass (imf12.hostedemail.com: domain of 34MS4YQYKCGEFKHCDQFNNFKD.BNLKHMTW-LLJU9BJ.NQF@flex--glider.bounces.google.com designates 209.85.221.74 as permitted sender) smtp.mailfrom=34MS4YQYKCGEFKHCDQFNNFKD.BNLKHMTW-LLJU9BJ.NQF@flex--glider.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com X-HE-Tag: 1639498972-727630 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: To avoid false positives, assume that reading from the task stack always produces initialized values. Signed-off-by: Alexander Potapenko --- Link: https://linux-review.googlesource.com/id/I9e2350bf3e88688dd83537e12a23456480141997 --- arch/x86/include/asm/unwind.h | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h index 2a1f8734416dc..51173b19ac4d5 100644 --- a/arch/x86/include/asm/unwind.h +++ b/arch/x86/include/asm/unwind.h @@ -129,18 +129,19 @@ unsigned long unwind_recover_ret_addr(struct unwind_state *state, } /* - * 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) \ -({ \ - unsigned long val; \ - if (task == current) \ - val = READ_ONCE(x); \ - else \ - val = READ_ONCE_NOCHECK(x); \ - val; \ +#define READ_ONCE_TASK_STACK(task, x) \ +({ \ + unsigned long val; \ + if (task == current && !IS_ENABLED(CONFIG_KMSAN)) \ + val = READ_ONCE(x); \ + else \ + val = READ_ONCE_NOCHECK(x); \ + val; \ }) static inline bool task_on_another_cpu(struct task_struct *task)