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Fri, 12 Mar 2021 07:08:30 -0800 (PST) Received: from elver.google.com ([2a00:79e0:15:13:d5de:d45f:f79c:cb62]) by smtp.gmail.com with ESMTPSA id j30sm9332276wrj.62.2021.03.12.07.08.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Mar 2021 07:08:29 -0800 (PST) Date: Fri, 12 Mar 2021 16:08:24 +0100 From: Marco Elver To: Andrey Konovalov Cc: Andrew Morton , Alexander Potapenko , Andrey Ryabinin , Dmitry Vyukov , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 05/11] kasan: docs: update boot parameters section Message-ID: References: <01364952f15789948f0627d6733b5cdf5209f83a.1615559068.git.andreyknvl@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <01364952f15789948f0627d6733b5cdf5209f83a.1615559068.git.andreyknvl@google.com> User-Agent: Mutt/2.0.5 (2021-01-21) X-Stat-Signature: rkgsxpmmhowoqeyb7nr1uztjck3519m3 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 3428AD7 Received-SPF: none (google.com>: No applicable sender policy available) receiver=imf12; identity=mailfrom; envelope-from=""; helo=mail-wr1-f47.google.com; client-ip=209.85.221.47 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615561708-504363 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 Fri, Mar 12, 2021 at 03:24PM +0100, Andrey Konovalov wrote: > 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. > > Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver > --- > Documentation/dev-tools/kasan.rst | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-) > > diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst > index cd12c890b888..1189be9b4cb5 100644 > --- a/Documentation/dev-tools/kasan.rst > +++ b/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``). > > @@ -185,8 +191,8 @@ 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 > ---------------------- > -- > 2.31.0.rc2.261.g7f71774620-goog >