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evm: prevent racing during tfm allocation

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There is a small chance of racing during tfm allocation.
This patch fixes it.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
Dmitry Kasatkin 2011-12-05 13:17:42 +02:00 committed by James Morris
parent 88d7ed3508
commit 143b01d332
1 changed files with 11 additions and 3 deletions
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14
security/integrity/evm/evm_crypto.c
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@ -28,9 +28,11 @@ static int evmkey_len = MAX_KEY_SIZE;
struct crypto_shash *hmac_tfm;
struct crypto_shash *hash_tfm;
static DEFINE_MUTEX(mutex);
static struct shash_desc *init_desc(const char type)
{
int rc;
long rc;
char *algo;
struct crypto_shash **tfm;
struct shash_desc *desc;
@ -44,12 +46,15 @@ static struct shash_desc *init_desc(const char type)
}
if (*tfm == NULL) {
mutex_lock(&mutex);
if (*tfm)
goto out;
*tfm = crypto_alloc_shash(algo, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(*tfm)) {
pr_err("Can not allocate %s (reason: %ld)\n",
algo, PTR_ERR(*tfm));
rc = PTR_ERR(*tfm);
pr_err("Can not allocate %s (reason: %ld)\n", algo, rc);
*tfm = NULL;
mutex_unlock(&mutex);
return ERR_PTR(rc);
}
if (type == EVM_XATTR_HMAC) {
@ -57,9 +62,12 @@ static struct shash_desc *init_desc(const char type)
if (rc) {
crypto_free_shash(*tfm);
*tfm = NULL;
mutex_unlock(&mutex);
return ERR_PTR(rc);
}
}
out:
mutex_unlock(&mutex);
}
desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(*tfm),