dm crypt: restructure essiv error path

Use kzfree for salt deallocation because it is derived from the volume
key.  Use a common error path in ESSIV constructor.

Required by a later patch which fixes the way key material is wiped
from memory.

Cc: stable@kernel.org
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 26 insertions, 20 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index bec5ac54e23e..2301d223f2ae 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -187,15 +187,15 @@ static void crypt_iv_essiv_dtr(struct crypt_config *cc)
 static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
                               const char *opts)
 {
-        struct crypto_cipher *essiv_tfm;
-        struct crypto_hash *hash_tfm;
+        struct crypto_cipher *essiv_tfm = NULL;
+        struct crypto_hash *hash_tfm = NULL;
         struct hash_desc desc;
         struct scatterlist sg;
         unsigned int saltsize;
-        u8 *salt;
+        u8 *salt = NULL;
         int err;
 
-        if (opts == NULL) {
+        if (!opts) {
                 ti->error = "Digest algorithm missing for ESSIV mode";
                 return -EINVAL;
         }
@@ -204,15 +204,16 @@ static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
         hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
         if (IS_ERR(hash_tfm)) {
                 ti->error = "Error initializing ESSIV hash";
-                return PTR_ERR(hash_tfm);
+                err = PTR_ERR(hash_tfm);
+                goto bad;
         }
 
         saltsize = crypto_hash_digestsize(hash_tfm);
-        salt = kmalloc(saltsize, GFP_KERNEL);
-        if (salt == NULL) {
+        salt = kzalloc(saltsize, GFP_KERNEL);
+        if (!salt) {
                 ti->error = "Error kmallocing salt storage in ESSIV";
-                crypto_free_hash(hash_tfm);
-                return -ENOMEM;
+                err = -ENOMEM;
+                goto bad;
         }
 
         sg_init_one(&sg, cc->key, cc->key_size);
@@ -220,39 +221,44 @@ static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
         desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
         err = crypto_hash_digest(&desc, &sg, cc->key_size, salt);
         crypto_free_hash(hash_tfm);
+        hash_tfm = NULL;
 
         if (err) {
                 ti->error = "Error calculating hash in ESSIV";
-                kfree(salt);
-                return err;
+                goto bad;
         }
 
         /* Setup the essiv_tfm with the given salt */
         essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
         if (IS_ERR(essiv_tfm)) {
                 ti->error = "Error allocating crypto tfm for ESSIV";
-                kfree(salt);
-                return PTR_ERR(essiv_tfm);
+                err = PTR_ERR(essiv_tfm);
+                goto bad;
         }
         if (crypto_cipher_blocksize(essiv_tfm) !=
             crypto_ablkcipher_ivsize(cc->tfm)) {
                 ti->error = "Block size of ESSIV cipher does "
                             "not match IV size of block cipher";
-                crypto_free_cipher(essiv_tfm);
-                kfree(salt);
-                return -EINVAL;
+                err = -EINVAL;
+                goto bad;
         }
         err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
         if (err) {
                 ti->error = "Failed to set key for ESSIV cipher";
-                crypto_free_cipher(essiv_tfm);
-                kfree(salt);
-                return err;
+                goto bad;
         }
-        kfree(salt);
+        kzfree(salt);
 
         cc->iv_gen_private.essiv.tfm = essiv_tfm;
         return 0;
+
+bad:
+        if (essiv_tfm && !IS_ERR(essiv_tfm))
+                crypto_free_cipher(essiv_tfm);
+        if (hash_tfm && !IS_ERR(hash_tfm))
+                crypto_free_hash(hash_tfm);
+        kzfree(salt);
+        return err;
 }
 
 static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)