The patch titled
Subject: kasan: docs: update boot parameters section
has been added to the -mm tree. Its filename is
kasan-docs-update-boot-parameters-section.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kasan-docs-update-boot-parameters-section.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kasan-docs-update-boot-parameters-section.patch
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------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
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@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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``).
@@ -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
----------------------
_
Patches currently in -mm which might be from andreyknvl@xxxxxxxxxx are
kasan-mm-fix-crash-with-hw_tags-and-debug_pagealloc.patch
kasan-fix-kasan_stack-dependency-for-hw_tags.patch
kasan-fix-per-page-tags-for-non-page_alloc-pages.patch
kasan-initialize-shadow-to-tag_invalid-for-sw_tags.patch
mm-kasan-dont-poison-boot-memory-with-tag-based-modes.patch
arm64-kasan-allow-to-init-memory-when-setting-tags.patch
kasan-init-memory-in-kasan_unpoison-for-hw_tags.patch
kasan-mm-integrate-page_alloc-init-with-hw_tags.patch
kasan-mm-integrate-slab-init_on_alloc-with-hw_tags.patch
kasan-mm-integrate-slab-init_on_free-with-hw_tags.patch
kasan-docs-clean-up-sections.patch
kasan-docs-update-overview-section.patch
kasan-docs-update-usage-section.patch
kasan-docs-update-error-reports-section.patch
kasan-docs-update-boot-parameters-section.patch
kasan-docs-update-generic-implementation-details-section.patch
kasan-docs-update-sw_tags-implementation-details-section.patch
kasan-docs-update-hw_tags-implementation-details-section.patch
kasan-docs-update-shadow-memory-section.patch
kasan-docs-update-ignoring-accesses-section.patch
kasan-docs-update-tests-section.patch
