Once an object is put into quarantine, we no longer own it, i.e. object
could leave the quarantine and be reallocated. So having set_track()
call after the quarantine_put() may corrupt slab objects.
BUG kmalloc-4096 (Not tainted): Poison overwritten
-----------------------------------------------------------------------------
Disabling lock debugging due to kernel taint
INFO: 0xffff8804540de850-0xffff8804540de857. First byte 0xb5 instead of 0x6b
...
INFO: Freed in qlist_free_all+0x42/0x100 age=75 cpu=3 pid=24492
__slab_free+0x1d6/0x2e0
___cache_free+0xb6/0xd0
qlist_free_all+0x83/0x100
quarantine_reduce+0x177/0x1b0
kasan_kmalloc+0xf3/0x100
kasan_slab_alloc+0x12/0x20
kmem_cache_alloc+0x109/0x3e0
mmap_region+0x53e/0xe40
do_mmap+0x70f/0xa50
vm_mmap_pgoff+0x147/0x1b0
SyS_mmap_pgoff+0x2c7/0x5b0
SyS_mmap+0x1b/0x30
do_syscall_64+0x1a0/0x4e0
return_from_SYSCALL_64+0x0/0x7a
INFO: Slab 0xffffea0011503600 objects=7 used=7 fp=0x (null)
flags=0x8000000000004080
INFO: Object 0xffff8804540de848 @offset=26696 fp=0xffff8804540dc588
Redzone ffff8804540de840: bb bb bb bb bb bb bb bb
........
Object ffff8804540de848: 6b 6b 6b 6b 6b 6b 6b 6b b5 52 00 00 f2 01 60 cc
kkkkkkkk.R....`.
Similarly, poisoning after the quarantine_put() leads to false positive
use-after-free reports:
BUG: KASAN: use-after-free in anon_vma_interval_tree_insert+0x304/0x430 at
addr ffff880405c540a0
Read of size 8 by task trinity-c0/3036
CPU: 0 PID: 3036 Comm: trinity-c0 Not tainted 4.7.0-think+ #9
Call Trace:
dump_stack+0x68/0x96
kasan_report_error+0x222/0x600
__asan_report_load8_noabort+0x61/0x70
anon_vma_interval_tree_insert+0x304/0x430
anon_vma_chain_link+0x91/0xd0
anon_vma_clone+0x136/0x3f0
anon_vma_fork+0x81/0x4c0
copy_process.part.47+0x2c43/0x5b20
_do_fork+0x16d/0xbd0
SyS_clone+0x19/0x20
do_syscall_64+0x1a0/0x4e0
entry_SYSCALL64_slow_path+0x25/0x25
Fix this by putting an object in the quarantine after all other
operations.
Fixes: 80a9201a5965 ("mm, kasan: switch SLUB to stackdepot, enable memory
quarantine for SLUB")
Link:
http://lkml.kernel.org/r/1470062715-14077-1-git-send-email-aryabi...@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com>
Reported-by: Dave Jones <da...@codemonkey.org.uk>
Reported-by: Vegard Nossum <vegard.nos...@oracle.com>
Reported-by: Sasha Levin <alexander.le...@verizon.com>
Acked-by: Alexander Potapenko <gli...@google.com>
Cc: Dmitry Vyukov <dvyu...@google.com>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
https://jira.sw.ru/browse/PSBM-69081
(cherry picked from commit 4a3d308d6674fabf213bce9c1a661ef43a85e515)
Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com>
---
mm/kasan/kasan.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 8a57f22560a4..d7c814309c3e 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -504,9 +504,9 @@ bool kasan_slab_free(struct kmem_cache *cache, void *object)
switch (alloc_info->state) {
case KASAN_STATE_ALLOC:
alloc_info->state = KASAN_STATE_QUARANTINE;
- quarantine_put(free_info, cache);
set_track(&free_info->track, GFP_NOWAIT);
kasan_poison_slab_free(cache, object);
+ quarantine_put(free_info, cache);
return true;
case KASAN_STATE_QUARANTINE:
case KASAN_STATE_FREE:
--
2.13.5
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