Commit 143b01d3 authored by Dmitry Kasatkin's avatar Dmitry Kasatkin Committed by James Morris

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 88d7ed35
...@@ -28,9 +28,11 @@ static int evmkey_len = MAX_KEY_SIZE; ...@@ -28,9 +28,11 @@ static int evmkey_len = MAX_KEY_SIZE;
struct crypto_shash *hmac_tfm; struct crypto_shash *hmac_tfm;
struct crypto_shash *hash_tfm; struct crypto_shash *hash_tfm;
static DEFINE_MUTEX(mutex);
static struct shash_desc *init_desc(const char type) static struct shash_desc *init_desc(const char type)
{ {
int rc; long rc;
char *algo; char *algo;
struct crypto_shash **tfm; struct crypto_shash **tfm;
struct shash_desc *desc; struct shash_desc *desc;
...@@ -44,12 +46,15 @@ static struct shash_desc *init_desc(const char type) ...@@ -44,12 +46,15 @@ static struct shash_desc *init_desc(const char type)
} }
if (*tfm == NULL) { if (*tfm == NULL) {
mutex_lock(&mutex);
if (*tfm)
goto out;
*tfm = crypto_alloc_shash(algo, 0, CRYPTO_ALG_ASYNC); *tfm = crypto_alloc_shash(algo, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(*tfm)) { if (IS_ERR(*tfm)) {
pr_err("Can not allocate %s (reason: %ld)\n",
algo, PTR_ERR(*tfm));
rc = PTR_ERR(*tfm); rc = PTR_ERR(*tfm);
pr_err("Can not allocate %s (reason: %ld)\n", algo, rc);
*tfm = NULL; *tfm = NULL;
mutex_unlock(&mutex);
return ERR_PTR(rc); return ERR_PTR(rc);
} }
if (type == EVM_XATTR_HMAC) { if (type == EVM_XATTR_HMAC) {
...@@ -57,9 +62,12 @@ static struct shash_desc *init_desc(const char type) ...@@ -57,9 +62,12 @@ static struct shash_desc *init_desc(const char type)
if (rc) { if (rc) {
crypto_free_shash(*tfm); crypto_free_shash(*tfm);
*tfm = NULL; *tfm = NULL;
mutex_unlock(&mutex);
return ERR_PTR(rc); return ERR_PTR(rc);
} }
} }
out:
mutex_unlock(&mutex);
} }
desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(*tfm), desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(*tfm),
......
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