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Fri, 12 Mar 2021 06:24:47 -0800 (PST) Date: Fri, 12 Mar 2021 15:24:28 +0100 In-Reply-To: Message-Id: <01364952f15789948f0627d6733b5cdf5209f83a.1615559068.git.andreyknvl@google.com> Mime-Version: 1.0 References: X-Mailer: git-send-email 2.31.0.rc2.261.g7f71774620-goog Subject: [PATCH v2 05/11] kasan: docs: update boot parameters section From: Andrey Konovalov To: Andrew Morton , Alexander Potapenko , Marco Elver Cc: Andrey Ryabinin , Dmitry Vyukov , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 83F2420003A1 X-Stat-Signature: phih35bpxbf6qfmgp3r888dxxs94iew3 Received-SPF: none (flex--andreyknvl.bounces.google.com>: No applicable sender policy available) receiver=imf28; identity=mailfrom; envelope-from="<3r3lLYAoKCNg4H7L8SEHPFAIIAF8.6IGFCHOR-GGEP46E.ILA@flex--andreyknvl.bounces.google.com>"; helo=mail-qv1-f73.google.com; client-ip=209.85.219.73 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615559089-571815 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: 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 --- 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