Revision f6ba488073fe8159851fe398cc3c5ee383bb4c7a authored by Vladimir Davydov on 18 August 2017, 22:16:08 UTC, committed by Linus Torvalds on 18 August 2017, 22:32:01 UTC
To avoid a possible deadlock, sysfs_slab_remove() schedules an
asynchronous work to delete sysfs entries corresponding to the kmem
cache. To ensure the cache isn't freed before the work function is
called, it takes a reference to the cache kobject. The reference is
supposed to be released by the work function.
However, the work function (sysfs_slab_remove_workfn()) does nothing in
case the cache sysfs entry has already been deleted, leaking the kobject
and the corresponding cache.
This may happen on a per memcg cache destruction, because sysfs entries
of a per memcg cache are deleted on memcg offline if the cache is empty
(see __kmemcg_cache_deactivate()).
The kmemleak report looks like this:
unreferenced object 0xffff9f798a79f540 (size 32):
comm "kworker/1:4", pid 15416, jiffies 4307432429 (age 28687.554s)
hex dump (first 32 bytes):
6b 6d 61 6c 6c 6f 63 2d 31 36 28 31 35 39 39 3a kmalloc-16(1599:
6e 65 77 72 6f 6f 74 29 00 23 6b c0 ff ff ff ff newroot).#k.....
backtrace:
kmemleak_alloc+0x4a/0xa0
__kmalloc_track_caller+0x148/0x2c0
kvasprintf+0x66/0xd0
kasprintf+0x49/0x70
memcg_create_kmem_cache+0xe6/0x160
memcg_kmem_cache_create_func+0x20/0x110
process_one_work+0x205/0x5d0
worker_thread+0x4e/0x3a0
kthread+0x109/0x140
ret_from_fork+0x2a/0x40
unreferenced object 0xffff9f79b6136840 (size 416):
comm "kworker/1:4", pid 15416, jiffies 4307432429 (age 28687.573s)
hex dump (first 32 bytes):
40 fb 80 c2 3e 33 00 00 00 00 00 40 00 00 00 00 @...>3.....@....
00 00 00 00 00 00 00 00 10 00 00 00 10 00 00 00 ................
backtrace:
kmemleak_alloc+0x4a/0xa0
kmem_cache_alloc+0x128/0x280
create_cache+0x3b/0x1e0
memcg_create_kmem_cache+0x118/0x160
memcg_kmem_cache_create_func+0x20/0x110
process_one_work+0x205/0x5d0
worker_thread+0x4e/0x3a0
kthread+0x109/0x140
ret_from_fork+0x2a/0x40
Fix the leak by adding the missing call to kobject_put() to
sysfs_slab_remove_workfn().
Link: http://lkml.kernel.org/r/20170812181134.25027-1-vdavydov.dev@gmail.com
Fixes: 3b7b314053d02 ("slub: make sysfs file removal asynchronous")
Signed-off-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Reported-by: Andrei Vagin <avagin@gmail.com>
Tested-by: Andrei Vagin <avagin@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org> [4.12.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 3010f87
audit.c
#include <linux/init.h>
#include <linux/types.h>
#include <linux/audit.h>
#include <asm/unistd.h>
static unsigned dir_class[] = {
#include <asm-generic/audit_dir_write.h>
~0U
};
static unsigned read_class[] = {
#include <asm-generic/audit_read.h>
~0U
};
static unsigned write_class[] = {
#include <asm-generic/audit_write.h>
~0U
};
static unsigned chattr_class[] = {
#include <asm-generic/audit_change_attr.h>
~0U
};
static unsigned signal_class[] = {
#include <asm-generic/audit_signal.h>
~0U
};
int audit_classify_arch(int arch)
{
if (audit_is_compat(arch))
return 1;
else
return 0;
}
int audit_classify_syscall(int abi, unsigned syscall)
{
if (audit_is_compat(abi))
return audit_classify_compat_syscall(abi, syscall);
switch(syscall) {
#ifdef __NR_open
case __NR_open:
return 2;
#endif
#ifdef __NR_openat
case __NR_openat:
return 3;
#endif
#ifdef __NR_socketcall
case __NR_socketcall:
return 4;
#endif
#ifdef __NR_execveat
case __NR_execveat:
#endif
case __NR_execve:
return 5;
default:
return 0;
}
}
static int __init audit_classes_init(void)
{
#ifdef CONFIG_AUDIT_COMPAT_GENERIC
audit_register_class(AUDIT_CLASS_WRITE_32, compat_write_class);
audit_register_class(AUDIT_CLASS_READ_32, compat_read_class);
audit_register_class(AUDIT_CLASS_DIR_WRITE_32, compat_dir_class);
audit_register_class(AUDIT_CLASS_CHATTR_32, compat_chattr_class);
audit_register_class(AUDIT_CLASS_SIGNAL_32, compat_signal_class);
#endif
audit_register_class(AUDIT_CLASS_WRITE, write_class);
audit_register_class(AUDIT_CLASS_READ, read_class);
audit_register_class(AUDIT_CLASS_DIR_WRITE, dir_class);
audit_register_class(AUDIT_CLASS_CHATTR, chattr_class);
audit_register_class(AUDIT_CLASS_SIGNAL, signal_class);
return 0;
}
__initcall(audit_classes_init);
Computing file changes ...
