The patch titled
Subject: kasan: dynamically allocate stack ring entries
has been added to the -mm mm-unstable branch. Its filename is
kasan-dynamically-allocate-stack-ring-entries.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kasan-dynamically-allocate-stack-ring-entries.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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 via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: kasan: dynamically allocate stack ring entries
Date: Mon, 5 Sep 2022 23:05:47 +0200
Instead of using a large static array, allocate the stack ring dynamically
via memblock_alloc().
The size of the stack ring is controlled by a new kasan.stack_ring_size
command-line parameter. When kasan.stack_ring_size is not provided, the
default value of 32 << 10 is used.
When the stack trace collection is disabled via kasan.stacktrace=off, the
stack ring is not allocated.
Link: https://lkml.kernel.org/r/03b82ab60db53427e9818e0b0c1971baa10c3cbc.1662411800.git.andreyknvl@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Peter Collingbourne <pcc@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/dev-tools/kasan.rst | 4 +++-
mm/kasan/kasan.h | 5 ++---
mm/kasan/report_tags.c | 4 ++--
mm/kasan/tags.c | 25 ++++++++++++++++++++++++-
4 files changed, 31 insertions(+), 7 deletions(-)
--- a/Documentation/dev-tools/kasan.rst~kasan-dynamically-allocate-stack-ring-entries
+++ a/Documentation/dev-tools/kasan.rst
@@ -112,10 +112,12 @@ parameter can be used to control panic a
if ``kasan_multi_shot`` is enabled.
Software and Hardware Tag-Based KASAN modes (see the section about various
-modes below) support disabling stack trace collection:
+modes below) support altering stack trace collection behavior:
- ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack
traces collection (default: ``on``).
+- ``kasan.stack_ring_size=<number of entries>`` specifies the number of entries
+ in the stack ring (default: ``32768``).
Hardware Tag-Based KASAN mode is intended for use in production as a security
mitigation. Therefore, it supports additional boot parameters that allow
--- a/mm/kasan/kasan.h~kasan-dynamically-allocate-stack-ring-entries
+++ a/mm/kasan/kasan.h
@@ -252,12 +252,11 @@ struct kasan_stack_ring_entry {
bool is_free;
};
-#define KASAN_STACK_RING_SIZE (32 << 10)
-
struct kasan_stack_ring {
rwlock_t lock;
+ size_t size;
atomic64_t pos;
- struct kasan_stack_ring_entry entries[KASAN_STACK_RING_SIZE];
+ struct kasan_stack_ring_entry *entries;
};
#endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
--- a/mm/kasan/report_tags.c~kasan-dynamically-allocate-stack-ring-entries
+++ a/mm/kasan/report_tags.c
@@ -56,11 +56,11 @@ void kasan_complete_mode_report_info(str
* entries relevant to the buggy object can be overwritten.
*/
- for (u64 i = pos - 1; i != pos - 1 - KASAN_STACK_RING_SIZE; i--) {
+ for (u64 i = pos - 1; i != pos - 1 - stack_ring.size; i--) {
if (alloc_found && free_found)
break;
- entry = &stack_ring.entries[i % KASAN_STACK_RING_SIZE];
+ entry = &stack_ring.entries[i % stack_ring.size];
/* Paired with smp_store_release() in save_stack_info(). */
ptr = (void *)smp_load_acquire(&entry->ptr);
--- a/mm/kasan/tags.c~kasan-dynamically-allocate-stack-ring-entries
+++ a/mm/kasan/tags.c
@@ -10,6 +10,7 @@
#include <linux/init.h>
#include <linux/kasan.h>
#include <linux/kernel.h>
+#include <linux/memblock.h>
#include <linux/memory.h>
#include <linux/mm.h>
#include <linux/static_key.h>
@@ -19,6 +20,8 @@
#include "kasan.h"
#include "../slab.h"
+#define KASAN_STACK_RING_SIZE_DEFAULT (32 << 10)
+
enum kasan_arg_stacktrace {
KASAN_ARG_STACKTRACE_DEFAULT,
KASAN_ARG_STACKTRACE_OFF,
@@ -52,6 +55,16 @@ static int __init early_kasan_flag_stack
}
early_param("kasan.stacktrace", early_kasan_flag_stacktrace);
+/* kasan.stack_ring_size=<number of entries> */
+static int __init early_kasan_flag_stack_ring_size(char *arg)
+{
+ if (!arg)
+ return -EINVAL;
+
+ return kstrtoul(arg, 0, &stack_ring.size);
+}
+early_param("kasan.stack_ring_size", early_kasan_flag_stack_ring_size);
+
void __init kasan_init_tags(void)
{
switch (kasan_arg_stacktrace) {
@@ -65,6 +78,16 @@ void __init kasan_init_tags(void)
static_branch_enable(&kasan_flag_stacktrace);
break;
}
+
+ if (kasan_stack_collection_enabled()) {
+ if (!stack_ring.size)
+ stack_ring.size = KASAN_STACK_RING_SIZE_DEFAULT;
+ stack_ring.entries = memblock_alloc(
+ sizeof(stack_ring.entries[0]) * stack_ring.size,
+ SMP_CACHE_BYTES);
+ if (WARN_ON(!stack_ring.entries))
+ static_branch_disable(&kasan_flag_stacktrace);
+ }
}
static void save_stack_info(struct kmem_cache *cache, void *object,
@@ -86,7 +109,7 @@ static void save_stack_info(struct kmem_
next:
pos = atomic64_fetch_add(1, &stack_ring.pos);
- entry = &stack_ring.entries[pos % KASAN_STACK_RING_SIZE];
+ entry = &stack_ring.entries[pos % stack_ring.size];
/* Detect stack ring entry slots that are being written to. */
old_ptr = READ_ONCE(entry->ptr);
_
Patches currently in -mm which might be from andreyknvl@xxxxxxxxxx are
kasan-check-kasan_no_free_meta-in-__kasan_metadata_size.patch
kasan-rename-kasan_set__info-to-kasan_save__info.patch
kasan-move-is_kmalloc-check-out-of-save_alloc_info.patch
kasan-split-save_alloc_info-implementations.patch
kasan-drop-config_kasan_tags_identify.patch
kasan-introduce-kasan_print_aux_stacks.patch
kasan-introduce-kasan_get_alloc_track.patch
kasan-introduce-kasan_init_object_meta.patch
kasan-clear-metadata-functions-for-tag-based-modes.patch
kasan-move-kasan_get__meta-to-genericc.patch
kasan-introduce-kasan_requires_meta.patch
kasan-introduce-kasan_init_cache_meta.patch
kasan-drop-config_kasan_generic-check-from-kasan_init_cache_meta.patch
kasan-only-define-kasan_metadata_size-for-generic-mode.patch
kasan-only-define-kasan_never_merge-for-generic-mode.patch
kasan-only-define-metadata-offsets-for-generic-mode.patch
kasan-only-define-metadata-structs-for-generic-mode.patch
kasan-only-define-kasan_cache_create-for-generic-mode.patch
kasan-pass-tagged-pointers-to-kasan_save_alloc-free_info.patch
kasan-move-kasan_get_alloc-free_track-definitions.patch
kasan-cosmetic-changes-in-reportc.patch
kasan-use-virt_addr_valid-in-kasan_addr_to_page-slab.patch
kasan-use-kasan_addr_to_slab-in-print_address_description.patch
kasan-make-kasan_addr_to_page-static.patch
kasan-simplify-print_report.patch
kasan-introduce-complete_report_info.patch
kasan-fill-in-cache-and-object-in-complete_report_info.patch
kasan-rework-function-arguments-in-reportc.patch
kasan-introduce-kasan_complete_mode_report_info.patch
kasan-implement-stack-ring-for-tag-based-modes.patch
kasan-support-kasanstacktrace-for-sw_tags.patch
kasan-dynamically-allocate-stack-ring-entries.patch
kasan-better-identify-bug-types-for-tag-based-modes.patch
kasan-add-another-use-after-free-test.patch
kasan-move-tests-to-mm-kasan.patch
