The patch titled
Subject: kasan: clarify that only first bug is reported in HW_TAGS
has been added to the -mm tree. Its filename is
kasan-clarify-that-only-first-bug-is-reported-in-hw_tags.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kasan-clarify-that-only-first-bug-is-reported-in-hw_tags.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kasan-clarify-that-only-first-bug-is-reported-in-hw_tags.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: kasan: clarify that only first bug is reported in HW_TAGS
Hwardware tag-based KASAN only reports the first found bug. After that MTE
tag checking gets disabled. Clarify this in comments and documentation.
Link: https://lkml.kernel.org/r/00383ba88a47c3f8342d12263c24bdf95527b07d.1612546384.git.andreyknvl@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Branislav Rankov <Branislav.Rankov@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx>
Cc: Kevin Brodsky <kevin.brodsky@xxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Peter Collingbourne <pcc@xxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/dev-tools/kasan.rst | 8 ++++++--
mm/kasan/hw_tags.c | 2 +-
2 files changed, 7 insertions(+), 3 deletions(-)
--- a/Documentation/dev-tools/kasan.rst~kasan-clarify-that-only-first-bug-is-reported-in-hw_tags
+++ a/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
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?
--------------------------------------------
--- a/mm/kasan/hw_tags.c~kasan-clarify-that-only-first-bug-is-reported-in-hw_tags
+++ a/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 */
_
Patches currently in -mm which might be from andreyknvl@xxxxxxxxxx are
kasan-prefix-global-functions-with-kasan_.patch
kasan-clarify-hw_tags-impact-on-tbi.patch
kasan-clean-up-comments-in-tests.patch
kasan-add-macros-to-simplify-checking-test-constraints.patch
kasan-add-match-all-tag-tests.patch
kasan-arm64-allow-using-kunit-tests-with-hw_tags-mode.patch
kasan-rename-config_test_kasan_module.patch
kasan-add-compiler-barriers-to-kunit_expect_kasan_fail.patch
kasan-adapt-kmalloc_uaf2-test-to-hw_tags-mode.patch
kasan-fix-memory-corruption-in-kasan_bitops_tags-test.patch
kasan-move-_ret_ip_-to-inline-wrappers.patch
kasan-fix-bug-detection-via-ksize-for-hw_tags-mode.patch
kasan-add-proper-page-allocator-tests.patch
kasan-add-a-test-for-kmem_cache_alloc-free_bulk.patch
kasan-dont-run-tests-when-kasan-is-not-enabled.patch
kfence-kasan-make-kfence-compatible-with-kasan-fix-2.patch
kasan-mm-dont-save-alloc-stacks-twice.patch
kasan-mm-optimize-kmalloc-poisoning.patch
kasan-optimize-large-kmalloc-poisoning.patch
kasan-clean-up-setting-free-info-in-kasan_slab_free.patch
kasan-unify-large-kfree-checks.patch
kasan-rework-krealloc-tests.patch
kasan-mm-fail-krealloc-on-freed-objects.patch
kasan-mm-optimize-krealloc-poisoning.patch
kasan-ensure-poisoning-size-alignment.patch
arm64-kasan-simplify-and-inline-mte-functions.patch
kasan-inline-hw_tags-helper-functions.patch
arm64-kasan-export-mte-symbols-for-kasan-tests.patch
kasan-clarify-that-only-first-bug-is-reported-in-hw_tags.patch
