From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: kasan, slab: make freelist stored without tags
Similarly to 680c37ae ("kasan, slub: move kasan_poison_slab hook before
page_address"), move kasan_poison_slab() before alloc_slabmgmt(), which
calls page_address(), to make page_address() return value to be
non-tagged. This, combined with calling kasan_reset_tag() for off-slab
slab management object, leads to freelist being stored non-tagged.
Link: http://lkml.kernel.org/r/dfb53b44a4d00de3879a05a9f04c1f55e584f7a1.1550602886.git.andreyknvl@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Tested-by: Qian Cai <cai@xxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Evgeniy Stepanov <eugenis@xxxxxxxxxx>
Cc: Kostya Serebryany <kcc@xxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/slab.c~kasan-slab-make-freelist-stored-without-tags
+++ a/mm/slab.c
@@ -2359,7 +2359,7 @@ static void *alloc_slabmgmt(struct kmem_
void *freelist;
void *addr = page_address(page);
- page->s_mem = kasan_reset_tag(addr) + colour_off;
+ page->s_mem = addr + colour_off;
page->active = 0;
if (OBJFREELIST_SLAB(cachep))
@@ -2368,6 +2368,7 @@ static void *alloc_slabmgmt(struct kmem_
/* Slab management obj is off-slab. */
freelist = kmem_cache_alloc_node(cachep->freelist_cache,
local_flags, nodeid);
+ freelist = kasan_reset_tag(freelist);
if (!freelist)
return NULL;
} else {
@@ -2681,6 +2682,13 @@ static struct page *cache_grow_begin(str
offset *= cachep->colour_off;
+ /*
+ * Call kasan_poison_slab() before calling alloc_slabmgmt(), so
+ * page_address() in the latter returns a non-tagged pointer,
+ * as it should be for slab pages.
+ */
+ kasan_poison_slab(page);
+
/* Get slab management. */
freelist = alloc_slabmgmt(cachep, page, offset,
local_flags & ~GFP_CONSTRAINT_MASK, page_node);
@@ -2689,7 +2697,6 @@ static struct page *cache_grow_begin(str
slab_map_pages(cachep, page, freelist);
- kasan_poison_slab(page);
cache_init_objs(cachep, page);
if (gfpflags_allow_blocking(local_flags))
_
