Revision d38a2b7a9c939e6d7329ab92b96559ccebf7b135 authored by Muchun Song on 24 July 2020, 04:15:27 UTC, committed by Linus Torvalds on 24 July 2020, 19:42:41 UTC
If the kmem_cache refcount is greater than one, we should not mark the
root kmem_cache as dying. If we mark the root kmem_cache dying
incorrectly, the non-root kmem_cache can never be destroyed. It
resulted in memory leak when memcg was destroyed. We can use the
following steps to reproduce.
1) Use kmem_cache_create() to create a new kmem_cache named A.
2) Coincidentally, the kmem_cache A is an alias for kmem_cache B,
so the refcount of B is just increased.
3) Use kmem_cache_destroy() to destroy the kmem_cache A, just
decrease the B's refcount but mark the B as dying.
4) Create a new memory cgroup and alloc memory from the kmem_cache
B. It leads to create a non-root kmem_cache for allocating memory.
5) When destroy the memory cgroup created in the step 4), the
non-root kmem_cache can never be destroyed.
If we repeat steps 4) and 5), this will cause a lot of memory leak. So
only when refcount reach zero, we mark the root kmem_cache as dying.
Fixes: 92ee383f6daa ("mm: fix race between kmem_cache destroy, create and deactivate")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200716165103.83462-1-songmuchun@bytedance.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 8d22a93
akcipher.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Public Key Encryption
*
* Copyright (c) 2015, Intel Corporation
* Authors: Tadeusz Struk <tadeusz.struk@intel.com>
*/
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/crypto.h>
#include <linux/compiler.h>
#include <crypto/algapi.h>
#include <linux/cryptouser.h>
#include <net/netlink.h>
#include <crypto/akcipher.h>
#include <crypto/internal/akcipher.h>
#include "internal.h"
#ifdef CONFIG_NET
static int crypto_akcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_akcipher rakcipher;
memset(&rakcipher, 0, sizeof(rakcipher));
strscpy(rakcipher.type, "akcipher", sizeof(rakcipher.type));
return nla_put(skb, CRYPTOCFGA_REPORT_AKCIPHER,
sizeof(rakcipher), &rakcipher);
}
#else
static int crypto_akcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
{
return -ENOSYS;
}
#endif
static void crypto_akcipher_show(struct seq_file *m, struct crypto_alg *alg)
__maybe_unused;
static void crypto_akcipher_show(struct seq_file *m, struct crypto_alg *alg)
{
seq_puts(m, "type : akcipher\n");
}
static void crypto_akcipher_exit_tfm(struct crypto_tfm *tfm)
{
struct crypto_akcipher *akcipher = __crypto_akcipher_tfm(tfm);
struct akcipher_alg *alg = crypto_akcipher_alg(akcipher);
alg->exit(akcipher);
}
static int crypto_akcipher_init_tfm(struct crypto_tfm *tfm)
{
struct crypto_akcipher *akcipher = __crypto_akcipher_tfm(tfm);
struct akcipher_alg *alg = crypto_akcipher_alg(akcipher);
if (alg->exit)
akcipher->base.exit = crypto_akcipher_exit_tfm;
if (alg->init)
return alg->init(akcipher);
return 0;
}
static void crypto_akcipher_free_instance(struct crypto_instance *inst)
{
struct akcipher_instance *akcipher = akcipher_instance(inst);
akcipher->free(akcipher);
}
static const struct crypto_type crypto_akcipher_type = {
.extsize = crypto_alg_extsize,
.init_tfm = crypto_akcipher_init_tfm,
.free = crypto_akcipher_free_instance,
#ifdef CONFIG_PROC_FS
.show = crypto_akcipher_show,
#endif
.report = crypto_akcipher_report,
.maskclear = ~CRYPTO_ALG_TYPE_MASK,
.maskset = CRYPTO_ALG_TYPE_MASK,
.type = CRYPTO_ALG_TYPE_AKCIPHER,
.tfmsize = offsetof(struct crypto_akcipher, base),
};
int crypto_grab_akcipher(struct crypto_akcipher_spawn *spawn,
struct crypto_instance *inst,
const char *name, u32 type, u32 mask)
{
spawn->base.frontend = &crypto_akcipher_type;
return crypto_grab_spawn(&spawn->base, inst, name, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_grab_akcipher);
struct crypto_akcipher *crypto_alloc_akcipher(const char *alg_name, u32 type,
u32 mask)
{
return crypto_alloc_tfm(alg_name, &crypto_akcipher_type, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_alloc_akcipher);
static void akcipher_prepare_alg(struct akcipher_alg *alg)
{
struct crypto_alg *base = &alg->base;
base->cra_type = &crypto_akcipher_type;
base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
base->cra_flags |= CRYPTO_ALG_TYPE_AKCIPHER;
}
static int akcipher_default_op(struct akcipher_request *req)
{
return -ENOSYS;
}
int crypto_register_akcipher(struct akcipher_alg *alg)
{
struct crypto_alg *base = &alg->base;
if (!alg->sign)
alg->sign = akcipher_default_op;
if (!alg->verify)
alg->verify = akcipher_default_op;
if (!alg->encrypt)
alg->encrypt = akcipher_default_op;
if (!alg->decrypt)
alg->decrypt = akcipher_default_op;
akcipher_prepare_alg(alg);
return crypto_register_alg(base);
}
EXPORT_SYMBOL_GPL(crypto_register_akcipher);
void crypto_unregister_akcipher(struct akcipher_alg *alg)
{
crypto_unregister_alg(&alg->base);
}
EXPORT_SYMBOL_GPL(crypto_unregister_akcipher);
int akcipher_register_instance(struct crypto_template *tmpl,
struct akcipher_instance *inst)
{
if (WARN_ON(!inst->free))
return -EINVAL;
akcipher_prepare_alg(&inst->alg);
return crypto_register_instance(tmpl, akcipher_crypto_instance(inst));
}
EXPORT_SYMBOL_GPL(akcipher_register_instance);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Generic public key cipher type");
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