From 97426f985729573cea06e82e271cc3929f1f5f8e Mon Sep 17 00:00:00 2001 From: Dmitry Kasatkin Date: Mon, 5 Dec 2011 13:17:42 +0200 Subject: evm: prevent racing during tfm allocation There is a small chance of racing during tfm allocation. This patch fixes it. Signed-off-by: Dmitry Kasatkin Acked-by: Mimi Zohar Signed-off-by: James Morris --- security/integrity/evm/evm_crypto.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'security') diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index 4ad657d88097..8738deff26fa 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -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), -- cgit v1.2.3