[PATCH v3 mm 13/13] kasan: clarify that only first bug is reported in HW_TAGS
From: Andrey Konovalov <hidden>
Date: 2021-02-05 17:45:42
Also in:
linux-mm, lkml
Subsystem:
documentation, documentation process, kasan, memory management, the rest · Maintainers:
Jonathan Corbet, Andrey Ryabinin, Andrew Morton, Linus Torvalds
Hwardware tag-based KASAN only reports the first found bug. After that MTE tag checking gets disabled. Clarify this in comments and documentation. Signed-off-by: Andrey Konovalov <redacted> --- Documentation/dev-tools/kasan.rst | 8 ++++++-- mm/kasan/hw_tags.c | 2 +- 2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
index e022b7506e37..1faabbe23e09 100644
--- a/Documentation/dev-tools/kasan.rst
+++ b/Documentation/dev-tools/kasan.rst@@ -155,7 +155,7 @@ Boot parameters ~~~~~~~~~~~~~~~ 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 +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.
@@ -166,7 +166,8 @@ particular KASAN features. ``off``). - ``kasan.fault=report`` or ``=panic`` controls whether to only print a KASAN - report or also panic the kernel (default: ``report``). + report or also panic the kernel (default: ``report``). Note, that tag + checking gets disabled after the first reported bug. For developers ~~~~~~~~~~~~~~
@@ -296,6 +297,9 @@ Note, that enabling CONFIG_KASAN_HW_TAGS always results in in-kernel TBI being enabled. Even when kasan.mode=off is provided, or when the hardware doesn't support MTE (but supports TBI). +Hardware tag-based KASAN only reports the first found bug. After that MTE tag +checking gets disabled. + What memory accesses are sanitised by KASAN? --------------------------------------------
diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index e529428e7a11..6c9285c906b8 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c@@ -48,7 +48,7 @@ EXPORT_SYMBOL(kasan_flag_enabled); /* Whether to collect alloc/free stack traces. */ DEFINE_STATIC_KEY_FALSE(kasan_flag_stacktrace); -/* Whether panic or disable tag checking on fault. */ +/* Whether to panic or print a report and disable tag checking on fault. */ bool kasan_flag_panic __ro_after_init; /* kasan=off/on */
--
2.30.0.365.g02bc693789-goog
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