[PATCH v2] crypto: drbg - make drbg_{ctr_bcc,kcapi_sym}() return *void*

[Sergey Shtylyov <s.shtylyov@omp.ru>]

From: Karina Yankevich <k.yankevich@omp.ru>

drgb_kcapi_sym() always returns 0, so make it return void instead.
Consequently, make drbg_ctr_bcc() return void too.

Found by Linux Verification Center (linuxtesting.org) with the Svace static
analysis tool.

[Sergey: fixed the subject, refreshed the patch]

Signed-off-by: Karina Yankevich <k.yankevich@omp.ru>
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>

---
The patch is against the master branch of Linus Torvalds' linux.git repo
(I'm unable to use the other repos on git.kernel.org and I have to update
Linus' repo from GitHub).

 crypto/drbg.c |   38 ++++++++++++--------------------------
 1 file changed, 12 insertions(+), 26 deletions(-)

Index: linux/crypto/drbg.c
===================================================================
--- linux.orig/crypto/drbg.c
+++ linux/crypto/drbg.c
@@ -296,8 +296,8 @@ MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes12
 
 static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
 				 const unsigned char *key);
-static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
-			  const struct drbg_string *in);
+static void drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
+			   const struct drbg_string *in);
 static int drbg_init_sym_kernel(struct drbg_state *drbg);
 static int drbg_fini_sym_kernel(struct drbg_state *drbg);
 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
@@ -306,11 +306,10 @@ static int drbg_kcapi_sym_ctr(struct drb
 #define DRBG_OUTSCRATCHLEN 256
 
 /* BCC function for CTR DRBG as defined in 10.4.3 */
-static int drbg_ctr_bcc(struct drbg_state *drbg,
-			unsigned char *out, const unsigned char *key,
-			struct list_head *in)
+static void drbg_ctr_bcc(struct drbg_state *drbg,
+			 unsigned char *out, const unsigned char *key,
+			 struct list_head *in)
 {
-	int ret = 0;
 	struct drbg_string *curr = NULL;
 	struct drbg_string data;
 	short cnt = 0;
@@ -327,9 +326,7 @@ static int drbg_ctr_bcc(struct drbg_stat
 			/* 10.4.3 step 4.2 */
 			if (drbg_blocklen(drbg) == cnt) {
 				cnt = 0;
-				ret = drbg_kcapi_sym(drbg, out, &data);
-				if (ret)
-					return ret;
+				drbg_kcapi_sym(drbg, out, &data);
 			}
 			out[cnt] ^= *pos;
 			pos++;
@@ -339,9 +336,7 @@ static int drbg_ctr_bcc(struct drbg_stat
 	}
 	/* 10.4.3 step 4.2 for last block */
 	if (cnt)
-		ret = drbg_kcapi_sym(drbg, out, &data);
-
-	return ret;
+		drbg_kcapi_sym(drbg, out, &data);
 }
 
 /*
@@ -388,7 +383,6 @@ static int drbg_ctr_df(struct drbg_state
 		       unsigned char *df_data, size_t bytes_to_return,
 		       struct list_head *seedlist)
 {
-	int ret = -EFAULT;
 	unsigned char L_N[8];
 	/* S3 is input */
 	struct drbg_string S1, S2, S4, cipherin;
@@ -459,9 +453,7 @@ static int drbg_ctr_df(struct drbg_state
 		 */
 		drbg_cpu_to_be32(i, iv);
 		/* 10.4.2 step 9.2 -- BCC and concatenation with temp */
-		ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);
-		if (ret)
-			goto out;
+		drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);
 		/* 10.4.2 step 9.3 */
 		i++;
 		templen += drbg_blocklen(drbg);
@@ -482,9 +474,7 @@ static int drbg_ctr_df(struct drbg_state
 		 * implicit as the key is only drbg_blocklen in size based on
 		 * the implementation of the cipher function callback
 		 */
-		ret = drbg_kcapi_sym(drbg, X, &cipherin);
-		if (ret)
-			goto out;
+		drbg_kcapi_sym(drbg, X, &cipherin);
 		blocklen = (drbg_blocklen(drbg) <
 				(bytes_to_return - generated_len)) ?
 			    drbg_blocklen(drbg) :
@@ -494,13 +484,10 @@ static int drbg_ctr_df(struct drbg_state
 		generated_len += blocklen;
 	}
 
-	ret = 0;
-
-out:
 	memset(iv, 0, drbg_blocklen(drbg));
 	memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
 	memset(pad, 0, drbg_blocklen(drbg));
-	return ret;
+	return 0;
 }
 
 /*
@@ -1806,15 +1793,14 @@ static void drbg_kcapi_symsetkey(struct
 	crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg)));
 }
 
-static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
-			  const struct drbg_string *in)
+static void drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
+			   const struct drbg_string *in)
 {
 	struct crypto_cipher *tfm = drbg->priv_data;
 
 	/* there is only component in *in */
 	BUG_ON(in->len < drbg_blocklen(drbg));
 	crypto_cipher_encrypt_one(tfm, outval, in->buf);
-	return 0;
 }
 
 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,