On Mon, Dec 07, 2015 at 05:09:21PM +0100, Dmitry Vyukov wrote:
> If your audit does not give any results, can you give me a patch that
> prints rcu callback submission stacks in KASAN reports?
Just because my brain is fried for today, I figured I'd give it a go.
Completely untested..
---
include/linux/slub_def.h | 2 ++
kernel/rcu/tree_plugin.h | 1 +
mm/slub.c | 34 ++++++++++++++++++++++++++++++++--
3 files changed, 35 insertions(+), 2 deletions(-)
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 33885118523c..445b586c0bfa 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -129,4 +129,6 @@ static inline void *virt_to_obj(struct kmem_cache *s,
void object_err(struct kmem_cache *s, struct page *page,
u8 *object, char *reason);
+void object_set_indirect(const void *addr);
+
#endif /* _LINUX_SLUB_DEF_H */
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 630c19772630..4e1e79e01e34 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -659,6 +659,7 @@ static void rcu_preempt_do_callbacks(void)
*/
void call_rcu(struct rcu_head *head, rcu_callback_t func)
{
+ object_set_indirect(head);
__call_rcu(head, func, rcu_state_p, -1, 0);
}
EXPORT_SYMBOL_GPL(call_rcu);
diff --git a/mm/slub.c b/mm/slub.c
index 46997517406e..6977dc7cffcd 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -196,7 +196,12 @@ struct track {
unsigned long when; /* When did the operation occur */
};
-enum track_item { TRACK_ALLOC, TRACK_FREE };
+enum track_item {
+ TRACK_ALLOC = 0,
+ TRACK_FREE,
+ TRACK_INDIRECT,
+ TRACK_NR,
+};
#ifdef CONFIG_SYSFS
static int sysfs_slab_add(struct kmem_cache *);
@@ -551,6 +556,7 @@ static void init_tracking(struct kmem_cache *s, void
*object)
set_track(s, object, TRACK_FREE, 0UL);
set_track(s, object, TRACK_ALLOC, 0UL);
+ set_track(s, object, TRACK_INDIRECT, 0UL);
}
static void print_track(const char *s, struct track *t)
@@ -579,6 +585,7 @@ static void print_tracking(struct kmem_cache *s, void
*object)
print_track("Allocated", get_track(s, object, TRACK_ALLOC));
print_track("Freed", get_track(s, object, TRACK_FREE));
+ print_track("Indirect", get_track(s, object, TRACK_INDIRECT));
}
static void print_page_info(struct page *page)
@@ -652,6 +659,29 @@ static void print_trailer(struct kmem_cache *s, struct
page *page, u8 *p)
dump_stack();
}
+void object_set_indirect(const void *addr)
+{
+ if ((addr >= (void *)PAGE_OFFSET) &&
+ (addr < high_memory)) {
+ struct page *page = virt_to_head_page(addr);
+
+ if (PageSlab(page)) {
+ void *object;
+ struct kmem_cache *cache = page->slab_cache;
+ void *last_object;
+
+ object = virt_to_obj(cache, page_address(page), addr);
+ last_object = page_address(page) +
+ page->objects * cache->size;
+
+ if (unlikely(object > last_object))
+ object = last_object; /* we hit into padding */
+
+ set_track(cache, object, TRACK_INDIRECT, (unsigned
long)addr);
+ }
+ }
+}
+
void object_err(struct kmem_cache *s, struct page *page,
u8 *object, char *reason)
{
@@ -767,7 +797,7 @@ static int check_pad_bytes(struct kmem_cache *s, struct
page *page, u8 *p)
if (s->flags & SLAB_STORE_USER)
/* We also have user information there */
- off += 2 * sizeof(struct track);
+ off += TRACK_NR * sizeof(struct track);
if (s->size == off)
return 1;
--
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