Skip to main content

Browse the archive

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 
mm: memcg/slab: fix memory leak at non-root kmem_cache destroy
 
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
Raw File
aegis.h 
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * AEGIS common definitions
 *
 * Copyright (c) 2018 Ondrej Mosnacek <omosnacek@gmail.com>
 * Copyright (c) 2018 Red Hat, Inc. All rights reserved.
 */

#ifndef _CRYPTO_AEGIS_H
#define _CRYPTO_AEGIS_H

#include <crypto/aes.h>
#include <linux/bitops.h>
#include <linux/types.h>

#define AEGIS_BLOCK_SIZE 16

union aegis_block {
	__le64 words64[AEGIS_BLOCK_SIZE / sizeof(__le64)];
	__le32 words32[AEGIS_BLOCK_SIZE / sizeof(__le32)];
	u8 bytes[AEGIS_BLOCK_SIZE];
};

#define AEGIS_BLOCK_ALIGN (__alignof__(union aegis_block))
#define AEGIS_ALIGNED(p) IS_ALIGNED((uintptr_t)p, AEGIS_BLOCK_ALIGN)

static __always_inline void crypto_aegis_block_xor(union aegis_block *dst,
						   const union aegis_block *src)
{
	dst->words64[0] ^= src->words64[0];
	dst->words64[1] ^= src->words64[1];
}

static __always_inline void crypto_aegis_block_and(union aegis_block *dst,
						   const union aegis_block *src)
{
	dst->words64[0] &= src->words64[0];
	dst->words64[1] &= src->words64[1];
}

static __always_inline void crypto_aegis_aesenc(union aegis_block *dst,
						const union aegis_block *src,
						const union aegis_block *key)
{
	const u8  *s  = src->bytes;
	const u32 *t = crypto_ft_tab[0];
	u32 d0, d1, d2, d3;

	d0 = t[s[ 0]] ^ rol32(t[s[ 5]], 8) ^ rol32(t[s[10]], 16) ^ rol32(t[s[15]], 24);
	d1 = t[s[ 4]] ^ rol32(t[s[ 9]], 8) ^ rol32(t[s[14]], 16) ^ rol32(t[s[ 3]], 24);
	d2 = t[s[ 8]] ^ rol32(t[s[13]], 8) ^ rol32(t[s[ 2]], 16) ^ rol32(t[s[ 7]], 24);
	d3 = t[s[12]] ^ rol32(t[s[ 1]], 8) ^ rol32(t[s[ 6]], 16) ^ rol32(t[s[11]], 24);

	dst->words32[0] = cpu_to_le32(d0) ^ key->words32[0];
	dst->words32[1] = cpu_to_le32(d1) ^ key->words32[1];
	dst->words32[2] = cpu_to_le32(d2) ^ key->words32[2];
	dst->words32[3] = cpu_to_le32(d3) ^ key->words32[3];
}

#endif /* _CRYPTO_AEGIS_H */
back to top