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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 82A3DC43217 for ; Tue, 26 Apr 2022 16:48:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353302AbiDZQva (ORCPT ); Tue, 26 Apr 2022 12:51:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45460 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353355AbiDZQu7 (ORCPT ); Tue, 26 Apr 2022 12:50:59 -0400 Received: from mail-ed1-x549.google.com (mail-ed1-x549.google.com [IPv6:2a00:1450:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B46E94833C for ; Tue, 26 Apr 2022 09:45:57 -0700 (PDT) Received: by mail-ed1-x549.google.com with SMTP id ee56-20020a056402293800b00425b0f5b9c6so7562932edb.9 for ; Tue, 26 Apr 2022 09:45:57 -0700 (PDT) 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=Fx98fFr6n4NVKGBzav2AZaWX3VRzhlrRB+7m3pCHiSE=; b=XHfBp7Cl9xVO2N8a97yhZbWVDGYXssOGKoCjey19oDLs3NuPvKFqJlX77OVyMj94Gt 2jjyaOrHBMMVqPlV8iHx1esMbi+0FDIhnzF7Cykz5C7cq/uxOyLSo3F2oQbehHxHtWWq J0Gr9w+xpCyeNSmgjOjL6MaF2r1Jb+P68Kxo24lt3IECVMYNwPiYSWt8f1OWxVrhhtpd NO15cOsJnLjPuQEWdNOcUO0Xa9QVwX7bjyI3Sb7JSEshKJQJE+Pg0L1D80PFDwJ2uTlH nrRZFhYPzn8Skr3KSaxneh2u7R3qXEV++ExcIhKQSHekMMa2AQX+GQFmuIwyxjASi21j HPqw== 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=Fx98fFr6n4NVKGBzav2AZaWX3VRzhlrRB+7m3pCHiSE=; b=lJIfVmZX2vV/dETVV/nlrAT8itEyIGEEZU4M5RjJutnvqM/X1ok1XI7H1VbfktIHrC OYnxvndATsiYDOt52GRmIxtJseul2eHeQlYAtedkuebcxz6YQM5brGKjTF+lE2i69Ha7 qeE9ep7ejZmXYXVOqbElut+s/brK4V844+VUakxAZwKMfv5GBjYHKuxHCveAT69UKn6D eru4nbvDkaEG27wbwHZvPvU9L5edcAsnN42wslg0neWCwW0Ya5z5C4UDiJCeRhJKYvCp vWEJvT/Q7Yht4o+d9CZMxBZNNjEdK3/EHxeKksANc7C2nZQNQZoZJIQJMRgTdcNoukg4 HHtQ== X-Gm-Message-State: AOAM531Ib/pT+VIEuLSgCpgIRaejKUKWei4rjK4myD1ss+w9/ujrj8+z J3ut+dLzxVg/y4N+dIb/RIiug1MLIuI= X-Google-Smtp-Source: ABdhPJz3WWkOPsikmC1Af3Hb7X8sg1uvJjDWagM85J5s9I3Wdek2Bn8waW8w9Db/kDe/JuhNTPmAIxhWeNI= X-Received: from glider.muc.corp.google.com ([2a00:79e0:15:13:d580:abeb:bf6d:5726]) (user=glider job=sendgmr) by 2002:a05:6402:34d2:b0:423:e6c4:3e9 with SMTP id w18-20020a05640234d200b00423e6c403e9mr26328332edc.372.1650991556120; Tue, 26 Apr 2022 09:45:56 -0700 (PDT) Date: Tue, 26 Apr 2022 18:43:06 +0200 In-Reply-To: <20220426164315.625149-1-glider@google.com> Message-Id: <20220426164315.625149-38-glider@google.com> Mime-Version: 1.0 References: <20220426164315.625149-1-glider@google.com> X-Mailer: git-send-email 2.36.0.rc2.479.g8af0fa9b8e-goog Subject: [PATCH v3 37/46] x86: 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 , 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 , Mark Rutland , Matthew Wilcox , "Michael S. Tsirkin" , Pekka Enberg , Peter Zijlstra , Petr Mladek , Steven Rostedt , Thomas Gleixner , Vasily Gorbik , Vegard Nossum , Vlastimil Babka , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org 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 7cede4dc21f00..87acc90875b74 100644 --- a/arch/x86/include/asm/unwind.h +++ b/arch/x86/include/asm/unwind.h @@ -128,18 +128,19 @@ 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) -- 2.36.0.rc2.479.g8af0fa9b8e-goog