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Subject[PATCH v7 07/12] mm: slub: introduce metadata_access_enable()/metadata_access_disable()
Date
Wrap access to object's metadata in external functions with
metadata_access_enable()/metadata_access_disable() function calls.

This hooks separates payload accesses from metadata accesses
which might be useful for different checkers (e.g. KASan).

Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
---
mm/slub.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/mm/slub.c b/mm/slub.c
index 0c01584..88ad8b8 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -467,13 +467,23 @@ static int slub_debug;
static char *slub_debug_slabs;
static int disable_higher_order_debug;

+static inline void metadata_access_enable(void)
+{
+}
+
+static inline void metadata_access_disable(void)
+{
+}
+
/*
* Object debugging
*/
static void print_section(char *text, u8 *addr, unsigned int length)
{
+ metadata_access_enable();
print_hex_dump(KERN_ERR, text, DUMP_PREFIX_ADDRESS, 16, 1, addr,
length, 1);
+ metadata_access_disable();
}

static struct track *get_track(struct kmem_cache *s, void *object,
@@ -503,7 +513,9 @@ static void set_track(struct kmem_cache *s, void *object,
trace.max_entries = TRACK_ADDRS_COUNT;
trace.entries = p->addrs;
trace.skip = 3;
+ metadata_access_enable();
save_stack_trace(&trace);
+ metadata_access_disable();

/* See rant in lockdep.c */
if (trace.nr_entries != 0 &&
@@ -677,7 +689,9 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page,
u8 *fault;
u8 *end;

+ metadata_access_enable();
fault = memchr_inv(start, value, bytes);
+ metadata_access_disable();
if (!fault)
return 1;

@@ -770,7 +784,9 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page)
if (!remainder)
return 1;

+ metadata_access_enable();
fault = memchr_inv(end - remainder, POISON_INUSE, remainder);
+ metadata_access_disable();
if (!fault)
return 1;
while (end > fault && end[-1] == POISON_INUSE)
--
2.1.3


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