From patchwork Fri Apr 30 06:00:24 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12232559 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=-15.7 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 BB22DC43461 for ; Fri, 30 Apr 2021 06:00:27 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6CEE661481 for ; Fri, 30 Apr 2021 06:00:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6CEE661481 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 0F02B94002D; Fri, 30 Apr 2021 02:00:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 004A18D000B; Fri, 30 Apr 2021 02:00:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E341394002D; Fri, 30 Apr 2021 02:00:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0044.hostedemail.com [216.40.44.44]) by kanga.kvack.org (Postfix) with ESMTP id C497E8D000B for ; Fri, 30 Apr 2021 02:00:26 -0400 (EDT) Received: from smtpin31.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 8C7E18249980 for ; Fri, 30 Apr 2021 06:00:26 +0000 (UTC) X-FDA: 78087983652.31.7942B48 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf12.hostedemail.com (Postfix) with ESMTP id 9FE8A3D3 for ; Fri, 30 Apr 2021 06:00:14 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 2C3226147E; Fri, 30 Apr 2021 06:00:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1619762425; bh=yYyjM1gx3YPkkoyq1XFB/4PjlVjd7cWZ6bxnz6ngS3c=; h=Date:From:To:Subject:In-Reply-To:From; b=chuqCoIiu9HoyEDfRQidykRWvZohbZGMmV9v5kyJ9W0ODBbitnns1P88MQ/wX9VMG ql4CG0ZF86xY0aAIWVwiDtlgpdeKY+p2cOOHao2wZO6U3zoOaANlelquGPl5h7HhED WdmTYncRemv2nJIBDQti5YRPAz1gl7F0MU7A4Vr8= Date: Thu, 29 Apr 2021 23:00:24 -0700 From: Andrew Morton To: akpm@linux-foundation.org, andreyknvl@google.com, aryabinin@virtuozzo.com, dvyukov@google.com, elver@google.com, glider@google.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 140/178] kasan: docs: update boot parameters section Message-ID: <20210430060024.6yRWN_SCu%akpm@linux-foundation.org> In-Reply-To: <20210429225251.02b6386d21b69255b4f6c163@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 9FE8A3D3 Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=chuqCoIi; dmarc=none; spf=pass (imf12.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Stat-Signature: 1cqfeeqsyytztkk3nfnnukcc8fzozk4p 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: 1619762414-665870 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: docs: update boot parameters section Update the "Boot parameters" section in KASAN documentation: - Mention panic_on_warn. - Mention kasan_multi_shot and its interaction with panic_on_warn. - Clarify kasan.fault=panic interaction with panic_on_warn. - A readability clean-up. Link: https://lkml.kernel.org/r/01364952f15789948f0627d6733b5cdf5209f83a.1615559068.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Dmitry Vyukov Signed-off-by: Andrew Morton --- Documentation/dev-tools/kasan.rst | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) --- a/Documentation/dev-tools/kasan.rst~kasan-docs-update-boot-parameters-section +++ a/Documentation/dev-tools/kasan.rst @@ -174,10 +174,16 @@ call_rcu() and workqueue queuing. Boot parameters ~~~~~~~~~~~~~~~ +KASAN is affected by the generic ``panic_on_warn`` command line parameter. +When it is enabled, KASAN panics the kernel after printing a bug report. + +By default, KASAN prints a bug report only for the first invalid memory access. +With ``kasan_multi_shot``, KASAN prints a report on every invalid access. This +effectively disables ``panic_on_warn`` for KASAN reports. + 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 -boot parameters that allow to disable KASAN competely or otherwise control -particular KASAN features. +boot parameters that allow disabling KASAN or controlling its features. - ``kasan=off`` or ``=on`` controls whether KASAN is enabled (default: ``on``). @@ -194,8 +200,8 @@ 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``). Note, that tag - checking gets disabled after the first reported bug. + report or also panic the kernel (default: ``report``). The panic happens even + if ``kasan_multi_shot`` is enabled. Implementation details ----------------------