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
cmac.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* CMAC: Cipher Block Mode for Authentication
*
* Copyright © 2013 Jussi Kivilinna <jussi.kivilinna@iki.fi>
*
* Based on work by:
* Copyright © 2013 Tom St Denis <tstdenis@elliptictech.com>
* Based on crypto/xcbc.c:
* Copyright © 2006 USAGI/WIDE Project,
* Author: Kazunori Miyazawa <miyazawa@linux-ipv6.org>
*/
#include <crypto/internal/hash.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
/*
* +------------------------
* | <parent tfm>
* +------------------------
* | cmac_tfm_ctx
* +------------------------
* | consts (block size * 2)
* +------------------------
*/
struct cmac_tfm_ctx {
struct crypto_cipher *child;
u8 ctx[];
};
/*
* +------------------------
* | <shash desc>
* +------------------------
* | cmac_desc_ctx
* +------------------------
* | odds (block size)
* +------------------------
* | prev (block size)
* +------------------------
*/
struct cmac_desc_ctx {
unsigned int len;
u8 ctx[];
};
static int crypto_cmac_digest_setkey(struct crypto_shash *parent,
const u8 *inkey, unsigned int keylen)
{
unsigned long alignmask = crypto_shash_alignmask(parent);
struct cmac_tfm_ctx *ctx = crypto_shash_ctx(parent);
unsigned int bs = crypto_shash_blocksize(parent);
__be64 *consts = PTR_ALIGN((void *)ctx->ctx,
(alignmask | (__alignof__(__be64) - 1)) + 1);
u64 _const[2];
int i, err = 0;
u8 msb_mask, gfmask;
err = crypto_cipher_setkey(ctx->child, inkey, keylen);
if (err)
return err;
/* encrypt the zero block */
memset(consts, 0, bs);
crypto_cipher_encrypt_one(ctx->child, (u8 *)consts, (u8 *)consts);
switch (bs) {
case 16:
gfmask = 0x87;
_const[0] = be64_to_cpu(consts[1]);
_const[1] = be64_to_cpu(consts[0]);
/* gf(2^128) multiply zero-ciphertext with u and u^2 */
for (i = 0; i < 4; i += 2) {
msb_mask = ((s64)_const[1] >> 63) & gfmask;
_const[1] = (_const[1] << 1) | (_const[0] >> 63);
_const[0] = (_const[0] << 1) ^ msb_mask;
consts[i + 0] = cpu_to_be64(_const[1]);
consts[i + 1] = cpu_to_be64(_const[0]);
}
break;
case 8:
gfmask = 0x1B;
_const[0] = be64_to_cpu(consts[0]);
/* gf(2^64) multiply zero-ciphertext with u and u^2 */
for (i = 0; i < 2; i++) {
msb_mask = ((s64)_const[0] >> 63) & gfmask;
_const[0] = (_const[0] << 1) ^ msb_mask;
consts[i] = cpu_to_be64(_const[0]);
}
break;
}
return 0;
}
static int crypto_cmac_digest_init(struct shash_desc *pdesc)
{
unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm);
struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
int bs = crypto_shash_blocksize(pdesc->tfm);
u8 *prev = PTR_ALIGN((void *)ctx->ctx, alignmask + 1) + bs;
ctx->len = 0;
memset(prev, 0, bs);
return 0;
}
static int crypto_cmac_digest_update(struct shash_desc *pdesc, const u8 *p,
unsigned int len)
{
struct crypto_shash *parent = pdesc->tfm;
unsigned long alignmask = crypto_shash_alignmask(parent);
struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
struct crypto_cipher *tfm = tctx->child;
int bs = crypto_shash_blocksize(parent);
u8 *odds = PTR_ALIGN((void *)ctx->ctx, alignmask + 1);
u8 *prev = odds + bs;
/* checking the data can fill the block */
if ((ctx->len + len) <= bs) {
memcpy(odds + ctx->len, p, len);
ctx->len += len;
return 0;
}
/* filling odds with new data and encrypting it */
memcpy(odds + ctx->len, p, bs - ctx->len);
len -= bs - ctx->len;
p += bs - ctx->len;
crypto_xor(prev, odds, bs);
crypto_cipher_encrypt_one(tfm, prev, prev);
/* clearing the length */
ctx->len = 0;
/* encrypting the rest of data */
while (len > bs) {
crypto_xor(prev, p, bs);
crypto_cipher_encrypt_one(tfm, prev, prev);
p += bs;
len -= bs;
}
/* keeping the surplus of blocksize */
if (len) {
memcpy(odds, p, len);
ctx->len = len;
}
return 0;
}
static int crypto_cmac_digest_final(struct shash_desc *pdesc, u8 *out)
{
struct crypto_shash *parent = pdesc->tfm;
unsigned long alignmask = crypto_shash_alignmask(parent);
struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
struct crypto_cipher *tfm = tctx->child;
int bs = crypto_shash_blocksize(parent);
u8 *consts = PTR_ALIGN((void *)tctx->ctx,
(alignmask | (__alignof__(__be64) - 1)) + 1);
u8 *odds = PTR_ALIGN((void *)ctx->ctx, alignmask + 1);
u8 *prev = odds + bs;
unsigned int offset = 0;
if (ctx->len != bs) {
unsigned int rlen;
u8 *p = odds + ctx->len;
*p = 0x80;
p++;
rlen = bs - ctx->len - 1;
if (rlen)
memset(p, 0, rlen);
offset += bs;
}
crypto_xor(prev, odds, bs);
crypto_xor(prev, consts + offset, bs);
crypto_cipher_encrypt_one(tfm, out, prev);
return 0;
}
static int cmac_init_tfm(struct crypto_tfm *tfm)
{
struct crypto_cipher *cipher;
struct crypto_instance *inst = (void *)tfm->__crt_alg;
struct crypto_cipher_spawn *spawn = crypto_instance_ctx(inst);
struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
cipher = crypto_spawn_cipher(spawn);
if (IS_ERR(cipher))
return PTR_ERR(cipher);
ctx->child = cipher;
return 0;
};
static void cmac_exit_tfm(struct crypto_tfm *tfm)
{
struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
crypto_free_cipher(ctx->child);
}
static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb)
{
struct shash_instance *inst;
struct crypto_cipher_spawn *spawn;
struct crypto_alg *alg;
unsigned long alignmask;
int err;
err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
if (err)
return err;
inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
if (!inst)
return -ENOMEM;
spawn = shash_instance_ctx(inst);
err = crypto_grab_cipher(spawn, shash_crypto_instance(inst),
crypto_attr_alg_name(tb[1]), 0, 0);
if (err)
goto err_free_inst;
alg = crypto_spawn_cipher_alg(spawn);
switch (alg->cra_blocksize) {
case 16:
case 8:
break;
default:
err = -EINVAL;
goto err_free_inst;
}
err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
if (err)
goto err_free_inst;
alignmask = alg->cra_alignmask;
inst->alg.base.cra_alignmask = alignmask;
inst->alg.base.cra_priority = alg->cra_priority;
inst->alg.base.cra_blocksize = alg->cra_blocksize;
inst->alg.digestsize = alg->cra_blocksize;
inst->alg.descsize =
ALIGN(sizeof(struct cmac_desc_ctx), crypto_tfm_ctx_alignment())
+ (alignmask & ~(crypto_tfm_ctx_alignment() - 1))
+ alg->cra_blocksize * 2;
inst->alg.base.cra_ctxsize =
ALIGN(sizeof(struct cmac_tfm_ctx), crypto_tfm_ctx_alignment())
+ ((alignmask | (__alignof__(__be64) - 1)) &
~(crypto_tfm_ctx_alignment() - 1))
+ alg->cra_blocksize * 2;
inst->alg.base.cra_init = cmac_init_tfm;
inst->alg.base.cra_exit = cmac_exit_tfm;
inst->alg.init = crypto_cmac_digest_init;
inst->alg.update = crypto_cmac_digest_update;
inst->alg.final = crypto_cmac_digest_final;
inst->alg.setkey = crypto_cmac_digest_setkey;
inst->free = shash_free_singlespawn_instance;
err = shash_register_instance(tmpl, inst);
if (err) {
err_free_inst:
shash_free_singlespawn_instance(inst);
}
return err;
}
static struct crypto_template crypto_cmac_tmpl = {
.name = "cmac",
.create = cmac_create,
.module = THIS_MODULE,
};
static int __init crypto_cmac_module_init(void)
{
return crypto_register_template(&crypto_cmac_tmpl);
}
static void __exit crypto_cmac_module_exit(void)
{
crypto_unregister_template(&crypto_cmac_tmpl);
}
subsys_initcall(crypto_cmac_module_init);
module_exit(crypto_cmac_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("CMAC keyed hash algorithm");
MODULE_ALIAS_CRYPTO("cmac");
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