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From: Andrey Konovalov <andreyknvl@google.com>
To: Andrew Morton <akpm@linux-foundation.org>,
	Alexander Potapenko <glider@google.com>,
	Marco Elver <elver@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	kasan-dev@googlegroups.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH 05/11] kasan: docs: update boot parameters section
Date: Thu, 11 Mar 2021 22:37:17 +0100	[thread overview]
Message-ID: <afdec1e3271c9560bb0eb56bf36d6e3613830562.1615498565.git.andreyknvl@google.com> (raw)
In-Reply-To: <f6efb2f36fc1f40eb22df027e6bc956cac71745e.1615498565.git.andreyknvl@google.com>

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 <andreyknvl@google.com>
---
 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 5fe43489e94e..2f939241349d 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


  parent reply	other threads:[~2021-03-11 21:38 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-11 21:37 [PATCH 01/11] kasan: docs: clean up sections Andrey Konovalov
2021-03-11 21:37 ` [PATCH 02/11] kasan: docs: update overview section Andrey Konovalov
2021-03-12 10:17   ` Marco Elver
2021-03-12 13:51     ` Andrey Konovalov
2021-03-11 21:37 ` [PATCH 03/11] kasan: docs: update usage section Andrey Konovalov
2021-03-11 21:37 ` [PATCH 04/11] kasan: docs: update error reports section Andrey Konovalov
2021-03-11 21:37 ` Andrey Konovalov [this message]
2021-03-11 21:37 ` [PATCH 06/11] kasan: docs: update GENERIC implementation details section Andrey Konovalov
2021-03-11 21:37 ` [PATCH 07/11] kasan: docs: update SW_TAGS " Andrey Konovalov
2021-03-11 21:37 ` [PATCH 08/11] kasan: docs: update HW_TAGS " Andrey Konovalov
2021-03-11 21:37 ` [PATCH 09/11] kasan: docs: update shadow memory section Andrey Konovalov
2021-03-12 10:52   ` Marco Elver
2021-03-12 13:52     ` Andrey Konovalov
2021-03-11 21:37 ` [PATCH 10/11] kasan: docs: update ignoring accesses section Andrey Konovalov
2021-03-12 11:02   ` Marco Elver
2021-03-12 14:07     ` Andrey Konovalov
2021-03-11 21:37 ` [PATCH 11/11] kasan: docs: update tests section Andrey Konovalov
2021-03-12 10:47   ` Marco Elver
2021-03-12 13:53     ` Andrey Konovalov

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