evie/android_kernel_oneplus_msm8998
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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
parent d21b594518
commit 97426f9857
1 changed files with 9 additions and 0 deletions
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9
security/integrity/evm/evm_crypto.c
View file

@ -27,26 +27,35 @@ static int evmkey_len = MAX_KEY_SIZE;
struct crypto_shash *hmac_tfm; struct crypto_shash *hmac_tfm;
static DEFINE_MUTEX(mutex);
static struct shash_desc *init_desc(void) static struct shash_desc *init_desc(void)
{ {
int rc; int rc;
struct shash_desc *desc; struct shash_desc *desc;
if (hmac_tfm == NULL) { if (hmac_tfm == NULL) {
mutex_lock(&mutex);
if (hmac_tfm)
goto out;
hmac_tfm = crypto_alloc_shash(evm_hmac, 0, CRYPTO_ALG_ASYNC); hmac_tfm = crypto_alloc_shash(evm_hmac, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(hmac_tfm)) { if (IS_ERR(hmac_tfm)) {
pr_err("Can not allocate %s (reason: %ld)\n", pr_err("Can not allocate %s (reason: %ld)\n",
evm_hmac, PTR_ERR(hmac_tfm)); evm_hmac, PTR_ERR(hmac_tfm));
rc = PTR_ERR(hmac_tfm); rc = PTR_ERR(hmac_tfm);
hmac_tfm = NULL; hmac_tfm = NULL;
mutex_unlock(&mutex);
return ERR_PTR(rc); return ERR_PTR(rc);
} }
rc = crypto_shash_setkey(hmac_tfm, evmkey, evmkey_len); rc = crypto_shash_setkey(hmac_tfm, evmkey, evmkey_len);
if (rc) { if (rc) {
crypto_free_shash(hmac_tfm); crypto_free_shash(hmac_tfm);
hmac_tfm = NULL; hmac_tfm = NULL;
mutex_unlock(&mutex);
return ERR_PTR(rc); return ERR_PTR(rc);
} }
out:
mutex_unlock(&mutex);
} }
desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac_tfm), desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac_tfm),