The patch titled
Subject: kasan: preassign tags to objects with ctors or SLAB_TYPESAFE_BY_RCU
has been added to the -mm tree. Its filename is
kasan-preassign-tags-to-objects-with-ctors-or-slab_typesafe_by_rcu.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kasan-preassign-tags-to-objects-with-ctors-or-slab_typesafe_by_rcu.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kasan-preassign-tags-to-objects-with-ctors-or-slab_typesafe_by_rcu.patch
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------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: kasan: preassign tags to objects with ctors or SLAB_TYPESAFE_BY_RCU
An object constructor can initialize pointers within this objects based on
the address of the object. Since the object address might be tagged, we
need to assign a tag before calling constructor.
The implemented approach is to assign tags to objects with constructors
when a slab is allocated and call constructors once as usual. The
downside is that such object would always have the same tag when it is
reallocated, so we won't catch use-after-frees on it.
Also pressign tags for objects from SLAB_TYPESAFE_BY_RCU caches, since
they can be validy accessed after having been freed.
Link: http://lkml.kernel.org/r/b2c17b6674f1737f981ffa6dca7fdfc059a88435.1543337629.git.andreyknvl@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reviewed-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/slab.c~kasan-preassign-tags-to-objects-with-ctors-or-slab_typesafe_by_rcu
+++ a/mm/slab.c
@@ -2574,7 +2574,7 @@ static void cache_init_objs(struct kmem_
for (i = 0; i < cachep->num; i++) {
objp = index_to_obj(cachep, page, i);
- kasan_init_slab_obj(cachep, objp);
+ objp = kasan_init_slab_obj(cachep, objp);
/* constructor could break poison info */
if (DEBUG == 0 && cachep->ctor) {
--- a/mm/slub.c~kasan-preassign-tags-to-objects-with-ctors-or-slab_typesafe_by_rcu
+++ a/mm/slub.c
@@ -1451,16 +1451,17 @@ static inline bool slab_free_freelist_ho
#endif
}
-static void setup_object(struct kmem_cache *s, struct page *page,
+static void *setup_object(struct kmem_cache *s, struct page *page,
void *object)
{
setup_object_debug(s, page, object);
- kasan_init_slab_obj(s, object);
+ object = kasan_init_slab_obj(s, object);
if (unlikely(s->ctor)) {
kasan_unpoison_object_data(s, object);
s->ctor(object);
kasan_poison_object_data(s, object);
}
+ return object;
}
/*
@@ -1568,16 +1569,16 @@ static bool shuffle_freelist(struct kmem
/* First entry is used as the base of the freelist */
cur = next_freelist_entry(s, page, &pos, start, page_limit,
freelist_count);
+ cur = setup_object(s, page, cur);
page->freelist = cur;
for (idx = 1; idx < page->objects; idx++) {
- setup_object(s, page, cur);
next = next_freelist_entry(s, page, &pos, start, page_limit,
freelist_count);
+ next = setup_object(s, page, next);
set_freepointer(s, cur, next);
cur = next;
}
- setup_object(s, page, cur);
set_freepointer(s, cur, NULL);
return true;
@@ -1599,7 +1600,7 @@ static struct page *allocate_slab(struct
struct page *page;
struct kmem_cache_order_objects oo = s->oo;
gfp_t alloc_gfp;
- void *start, *p;
+ void *start, *p, *next;
int idx, order;
bool shuffle;
@@ -1651,13 +1652,16 @@ static struct page *allocate_slab(struct
if (!shuffle) {
for_each_object_idx(p, idx, s, start, page->objects) {
- setup_object(s, page, p);
- if (likely(idx < page->objects))
- set_freepointer(s, p, p + s->size);
- else
+ if (likely(idx < page->objects)) {
+ next = p + s->size;
+ next = setup_object(s, page, next);
+ set_freepointer(s, p, next);
+ } else
set_freepointer(s, p, NULL);
}
- page->freelist = fixup_red_left(s, start);
+ start = fixup_red_left(s, start);
+ start = setup_object(s, page, start);
+ page->freelist = start;
}
page->inuse = page->objects;
_
Patches currently in -mm which might be from andreyknvl@xxxxxxxxxx are
kasan-mm-change-hooks-signatures.patch
kasan-slub-handle-pointer-tags-in-early_kmem_cache_node_alloc.patch
kasan-move-common-generic-and-tag-based-code-to-commonc.patch
kasan-rename-source-files-to-reflect-the-new-naming-scheme.patch
kasan-add-config_kasan_generic-and-config_kasan_sw_tags.patch
kasan-arm64-adjust-shadow-size-for-tag-based-mode.patch
kasan-rename-kasan_zero_page-to-kasan_early_shadow_page.patch
kasan-initialize-shadow-to-0xff-for-tag-based-mode.patch
arm64-move-untagged_addr-macro-from-uaccessh-to-memoryh.patch
kasan-add-tag-related-helper-functions.patch
kasan-arm64-untag-address-in-_virt_addr_is_linear.patch
kasan-preassign-tags-to-objects-with-ctors-or-slab_typesafe_by_rcu.patch
kasan-arm64-fix-up-fault-handling-logic.patch
kasan-arm64-enable-top-byte-ignore-for-the-kernel.patch
kasan-mm-perform-untagged-pointers-comparison-in-krealloc.patch
kasan-split-out-generic_reportc-from-reportc.patch
kasan-add-bug-reporting-routines-for-tag-based-mode.patch
mm-move-obj_to_index-to-include-linux-slab_defh.patch
kasan-add-hooks-implementation-for-tag-based-mode.patch
kasan-arm64-add-brk-handler-for-inline-instrumentation.patch
kasan-mm-arm64-tag-non-slab-memory-allocated-via-pagealloc.patch
kasan-add-__must_check-annotations-to-kasan-hooks.patch
kasan-arm64-select-have_arch_kasan_sw_tags.patch
kasan-update-documentation.patch
kasan-add-spdx-license-identifier-mark-to-source-files.patch
