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Commit 97426f98 authored by Dmitry Kasatkin's avatar Dmitry Kasatkin
Browse files

evm: prevent racing during tfm allocation 



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

Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@intel.com>
Acked-by: default avatarMimi Zohar <zohar@us.ibm.com>
Signed-off-by: default avatarJames Morris <jmorris@namei.org>
parent d21b5945

security/integrity/evm/evm_crypto.c

+9 −0
Original line number Diff line number Diff line
@@ -27,26 +27,35 @@ static int evmkey_len = MAX_KEY_SIZE; 


struct crypto_shash *hmac_tfm;



static DEFINE_MUTEX(mutex);



static struct shash_desc *init_desc(void)

{

	int rc;

	struct shash_desc *desc;



	if (hmac_tfm == NULL) {

		mutex_lock(&mutex);

		if (hmac_tfm)

			goto out;

		hmac_tfm = crypto_alloc_shash(evm_hmac, 0, CRYPTO_ALG_ASYNC);

		if (IS_ERR(hmac_tfm)) {

			pr_err("Can not allocate %s (reason: %ld)\n",

			       evm_hmac, PTR_ERR(hmac_tfm));

			rc = PTR_ERR(hmac_tfm);

			hmac_tfm = NULL;

			mutex_unlock(&mutex);

			return ERR_PTR(rc);

		}

		rc = crypto_shash_setkey(hmac_tfm, evmkey, evmkey_len);

		if (rc) {

			crypto_free_shash(hmac_tfm);

			hmac_tfm = NULL;

			mutex_unlock(&mutex);

			return ERR_PTR(rc);

		}

out:

		mutex_unlock(&mutex);

	}



	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac_tfm),