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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 E9006C433DB for ; Fri, 26 Feb 2021 01:20:42 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 76E9364F2C for ; Fri, 26 Feb 2021 01:20:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 76E9364F2C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1137A6B00D0; Thu, 25 Feb 2021 20:20:42 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 09D526B00D1; Thu, 25 Feb 2021 20:20:42 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EA6786B00D2; Thu, 25 Feb 2021 20:20:41 -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 D27BF6B00D0 for ; Thu, 25 Feb 2021 20:20:41 -0500 (EST) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id AA34518038B5B for ; Fri, 26 Feb 2021 01:20:41 +0000 (UTC) X-FDA: 77858664282.20.771DD27 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf12.hostedemail.com (Postfix) with ESMTP id EE1DA13A for ; Fri, 26 Feb 2021 01:20:34 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 5E5CD64F31; Fri, 26 Feb 2021 01:20:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1614302440; bh=XL5Lbg9FpnZx+sRTQQpxNRMyW+riWGVdvnrvVqAyq0s=; h=Date:From:To:Subject:In-Reply-To:From; b=ubel/t07n32fMkSSN949MowZRVGWL+JGerNhB0zA1H8b+pzvp6Exk/wAYyHRUX31F l+SKqIL44sAQfyiWnWKRjLl8G75xGsG0hndva0o70reaZQeQqUyLDGaMWptzf9/JIO dN2tiEtYCftft1qxTqHx1FxlJETdlYIY1vSJf+4o= Date: Thu, 25 Feb 2021 17:20:38 -0800 From: Andrew Morton To: akpm@linux-foundation.org, andreyknvl@google.com, aryabinin@virtuozzo.com, Branislav.Rankov@arm.com, catalin.marinas@arm.com, dvyukov@google.com, elver@google.com, eugenis@google.com, glider@google.com, kevin.brodsky@arm.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, pcc@google.com, torvalds@linux-foundation.org, vincenzo.frascino@arm.com, will.deacon@arm.com Subject: [patch 081/118] kasan: clarify that only first bug is reported in HW_TAGS Message-ID: <20210226012038.w5208Ozub%akpm@linux-foundation.org> In-Reply-To: <20210225171452.713967e96554bb6a53e44a19@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Stat-Signature: eabwa8tkursf9copw1d3enw5drij898z X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: EE1DA13A Received-SPF: none (linux-foundation.org>: No applicable sender policy available) receiver=imf12; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1614302434-511751 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: From: Andrey Konovalov Subject: kasan: clarify that only first bug is reported in HW_TAGS Hwardware tag-based KASAN only reports the first found bug. After that MTE tag checking gets disabled. Clarify this in comments and documentation. Link: https://lkml.kernel.org/r/00383ba88a47c3f8342d12263c24bdf95527b07d.1612546384.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton --- Documentation/dev-tools/kasan.rst | 8 ++++++-- mm/kasan/hw_tags.c | 2 +- 2 files changed, 7 insertions(+), 3 deletions(-) --- a/Documentation/dev-tools/kasan.rst~kasan-clarify-that-only-first-bug-is-reported-in-hw_tags +++ a/Documentation/dev-tools/kasan.rst @@ -155,7 +155,7 @@ Boot parameters ~~~~~~~~~~~~~~~ Hardware tag-based KASAN mode (see the section about various modes below) is -intended for use in production as a security mitigation. Therefore it supports +intended for use in production as a security mitigation. Therefore, it supports boot parameters that allow to disable KASAN competely or otherwise control particular KASAN features. @@ -165,7 +165,8 @@ particular KASAN features. traces collection (default: ``on``). - ``kasan.fault=report`` or ``=panic`` controls whether to only print a KASAN - report or also panic the kernel (default: ``report``). + report or also panic the kernel (default: ``report``). Note, that tag + checking gets disabled after the first reported bug. For developers ~~~~~~~~~~~~~~ @@ -295,6 +296,9 @@ Note, that enabling CONFIG_KASAN_HW_TAGS enabled. Even when kasan.mode=off is provided, or when the hardware doesn't support MTE (but supports TBI). +Hardware tag-based KASAN only reports the first found bug. After that MTE tag +checking gets disabled. + What memory accesses are sanitised by KASAN? -------------------------------------------- --- a/mm/kasan/hw_tags.c~kasan-clarify-that-only-first-bug-is-reported-in-hw_tags +++ a/mm/kasan/hw_tags.c @@ -48,7 +48,7 @@ EXPORT_SYMBOL(kasan_flag_enabled); /* Whether to collect alloc/free stack traces. */ DEFINE_STATIC_KEY_FALSE(kasan_flag_stacktrace); -/* Whether panic or disable tag checking on fault. */ +/* Whether to panic or print a report and disable tag checking on fault. */ bool kasan_flag_panic __ro_after_init; /* kasan=off/on */ _