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>
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md4.c
/*
* Cryptographic API.
*
* MD4 Message Digest Algorithm (RFC1320).
*
* Implementation derived from Andrew Tridgell and Steve French's
* CIFS MD4 implementation, and the cryptoapi implementation
* originally based on the public domain implementation written
* by Colin Plumb in 1993.
*
* Copyright (c) Andrew Tridgell 1997-1998.
* Modified by Steve French (sfrench@us.ibm.com) 2002
* Copyright (c) Cryptoapi developers.
* Copyright (c) 2002 David S. Miller (davem@redhat.com)
* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
*/
#include <crypto/internal/hash.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/types.h>
#include <asm/byteorder.h>
#define MD4_DIGEST_SIZE 16
#define MD4_HMAC_BLOCK_SIZE 64
#define MD4_BLOCK_WORDS 16
#define MD4_HASH_WORDS 4
struct md4_ctx {
u32 hash[MD4_HASH_WORDS];
u32 block[MD4_BLOCK_WORDS];
u64 byte_count;
};
static inline u32 lshift(u32 x, unsigned int s)
{
x &= 0xFFFFFFFF;
return ((x << s) & 0xFFFFFFFF) | (x >> (32 - s));
}
static inline u32 F(u32 x, u32 y, u32 z)
{
return (x & y) | ((~x) & z);
}
static inline u32 G(u32 x, u32 y, u32 z)
{
return (x & y) | (x & z) | (y & z);
}
static inline u32 H(u32 x, u32 y, u32 z)
{
return x ^ y ^ z;
}
#define ROUND1(a,b,c,d,k,s) (a = lshift(a + F(b,c,d) + k, s))
#define ROUND2(a,b,c,d,k,s) (a = lshift(a + G(b,c,d) + k + (u32)0x5A827999,s))
#define ROUND3(a,b,c,d,k,s) (a = lshift(a + H(b,c,d) + k + (u32)0x6ED9EBA1,s))
static void md4_transform(u32 *hash, u32 const *in)
{
u32 a, b, c, d;
a = hash[0];
b = hash[1];
c = hash[2];
d = hash[3];
ROUND1(a, b, c, d, in[0], 3);
ROUND1(d, a, b, c, in[1], 7);
ROUND1(c, d, a, b, in[2], 11);
ROUND1(b, c, d, a, in[3], 19);
ROUND1(a, b, c, d, in[4], 3);
ROUND1(d, a, b, c, in[5], 7);
ROUND1(c, d, a, b, in[6], 11);
ROUND1(b, c, d, a, in[7], 19);
ROUND1(a, b, c, d, in[8], 3);
ROUND1(d, a, b, c, in[9], 7);
ROUND1(c, d, a, b, in[10], 11);
ROUND1(b, c, d, a, in[11], 19);
ROUND1(a, b, c, d, in[12], 3);
ROUND1(d, a, b, c, in[13], 7);
ROUND1(c, d, a, b, in[14], 11);
ROUND1(b, c, d, a, in[15], 19);
ROUND2(a, b, c, d,in[ 0], 3);
ROUND2(d, a, b, c, in[4], 5);
ROUND2(c, d, a, b, in[8], 9);
ROUND2(b, c, d, a, in[12], 13);
ROUND2(a, b, c, d, in[1], 3);
ROUND2(d, a, b, c, in[5], 5);
ROUND2(c, d, a, b, in[9], 9);
ROUND2(b, c, d, a, in[13], 13);
ROUND2(a, b, c, d, in[2], 3);
ROUND2(d, a, b, c, in[6], 5);
ROUND2(c, d, a, b, in[10], 9);
ROUND2(b, c, d, a, in[14], 13);
ROUND2(a, b, c, d, in[3], 3);
ROUND2(d, a, b, c, in[7], 5);
ROUND2(c, d, a, b, in[11], 9);
ROUND2(b, c, d, a, in[15], 13);
ROUND3(a, b, c, d,in[ 0], 3);
ROUND3(d, a, b, c, in[8], 9);
ROUND3(c, d, a, b, in[4], 11);
ROUND3(b, c, d, a, in[12], 15);
ROUND3(a, b, c, d, in[2], 3);
ROUND3(d, a, b, c, in[10], 9);
ROUND3(c, d, a, b, in[6], 11);
ROUND3(b, c, d, a, in[14], 15);
ROUND3(a, b, c, d, in[1], 3);
ROUND3(d, a, b, c, in[9], 9);
ROUND3(c, d, a, b, in[5], 11);
ROUND3(b, c, d, a, in[13], 15);
ROUND3(a, b, c, d, in[3], 3);
ROUND3(d, a, b, c, in[11], 9);
ROUND3(c, d, a, b, in[7], 11);
ROUND3(b, c, d, a, in[15], 15);
hash[0] += a;
hash[1] += b;
hash[2] += c;
hash[3] += d;
}
static inline void md4_transform_helper(struct md4_ctx *ctx)
{
le32_to_cpu_array(ctx->block, ARRAY_SIZE(ctx->block));
md4_transform(ctx->hash, ctx->block);
}
static int md4_init(struct shash_desc *desc)
{
struct md4_ctx *mctx = shash_desc_ctx(desc);
mctx->hash[0] = 0x67452301;
mctx->hash[1] = 0xefcdab89;
mctx->hash[2] = 0x98badcfe;
mctx->hash[3] = 0x10325476;
mctx->byte_count = 0;
return 0;
}
static int md4_update(struct shash_desc *desc, const u8 *data, unsigned int len)
{
struct md4_ctx *mctx = shash_desc_ctx(desc);
const u32 avail = sizeof(mctx->block) - (mctx->byte_count & 0x3f);
mctx->byte_count += len;
if (avail > len) {
memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
data, len);
return 0;
}
memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
data, avail);
md4_transform_helper(mctx);
data += avail;
len -= avail;
while (len >= sizeof(mctx->block)) {
memcpy(mctx->block, data, sizeof(mctx->block));
md4_transform_helper(mctx);
data += sizeof(mctx->block);
len -= sizeof(mctx->block);
}
memcpy(mctx->block, data, len);
return 0;
}
static int md4_final(struct shash_desc *desc, u8 *out)
{
struct md4_ctx *mctx = shash_desc_ctx(desc);
const unsigned int offset = mctx->byte_count & 0x3f;
char *p = (char *)mctx->block + offset;
int padding = 56 - (offset + 1);
*p++ = 0x80;
if (padding < 0) {
memset(p, 0x00, padding + sizeof (u64));
md4_transform_helper(mctx);
p = (char *)mctx->block;
padding = 56;
}
memset(p, 0, padding);
mctx->block[14] = mctx->byte_count << 3;
mctx->block[15] = mctx->byte_count >> 29;
le32_to_cpu_array(mctx->block, (sizeof(mctx->block) -
sizeof(u64)) / sizeof(u32));
md4_transform(mctx->hash, mctx->block);
cpu_to_le32_array(mctx->hash, ARRAY_SIZE(mctx->hash));
memcpy(out, mctx->hash, sizeof(mctx->hash));
memset(mctx, 0, sizeof(*mctx));
return 0;
}
static struct shash_alg alg = {
.digestsize = MD4_DIGEST_SIZE,
.init = md4_init,
.update = md4_update,
.final = md4_final,
.descsize = sizeof(struct md4_ctx),
.base = {
.cra_name = "md4",
.cra_driver_name = "md4-generic",
.cra_blocksize = MD4_HMAC_BLOCK_SIZE,
.cra_module = THIS_MODULE,
}
};
static int __init md4_mod_init(void)
{
return crypto_register_shash(&alg);
}
static void __exit md4_mod_fini(void)
{
crypto_unregister_shash(&alg);
}
subsys_initcall(md4_mod_init);
module_exit(md4_mod_fini);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("MD4 Message Digest Algorithm");
MODULE_ALIAS_CRYPTO("md4");
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