[PATCH 1/3] crypto-ansi_cprng: Use common error handling code in get_prng_bytes()

[SF Markus Elfring]

From: Markus Elfring <elfr...@users.sourceforge.net>
Date: Sat, 21 Oct 2017 15:17:52 +0200

Adjust jump targets so that a bit of exception handling can be better
reused at the end of this function.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfr...@users.sourceforge.net>
---
 crypto/ansi_cprng.c | 34 ++++++++++++++++------------------
 1 file changed, 16 insertions(+), 18 deletions(-)

diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c
index eff337ce9003..111c8982a47f 100644
--- a/crypto/ansi_cprng.c
+++ b/crypto/ansi_cprng.c
@@ -195,7 +195,7 @@ static int get_prng_bytes(char *buf, size_t nbytes, struct 
prng_context *ctx,
 
        err = -EINVAL;
        if (ctx->flags & PRNG_NEED_RESET)
-               goto done;
+               goto unlock;
 
        /*
         * If the FIXED_SIZE flag is on, only return whole blocks of
@@ -204,7 +204,7 @@ static int get_prng_bytes(char *buf, size_t nbytes, struct 
prng_context *ctx,
        err = -EINVAL;
        if (ctx->flags & PRNG_FIXED_SIZE) {
                if (nbytes < DEFAULT_BLK_SZ)
-                       goto done;
+                       goto unlock;
                byte_count = DEFAULT_BLK_SZ;
        }
 
@@ -219,13 +219,9 @@ static int get_prng_bytes(char *buf, size_t nbytes, struct 
prng_context *ctx,
 
 
 remainder:
-       if (ctx->rand_data_valid == DEFAULT_BLK_SZ) {
-               if (_get_more_prng_bytes(ctx, do_cont_test) < 0) {
-                       memset(buf, 0, nbytes);
-                       err = -EINVAL;
-                       goto done;
-               }
-       }
+       if (ctx->rand_data_valid == DEFAULT_BLK_SZ &&
+           _get_more_prng_bytes(ctx, do_cont_test) < 0)
+               goto reset_memory;
 
        /*
         * Copy any data less than an entire block
@@ -238,7 +234,7 @@ static int get_prng_bytes(char *buf, size_t nbytes, struct 
prng_context *ctx,
                        byte_count--;
                        ctx->rand_data_valid++;
                        if (byte_count == 0)
-                               goto done;
+                               goto unlock;
                }
        }
 
@@ -246,13 +242,10 @@ static int get_prng_bytes(char *buf, size_t nbytes, 
struct prng_context *ctx,
         * Now copy whole blocks
         */
        for (; byte_count >= DEFAULT_BLK_SZ; byte_count -= DEFAULT_BLK_SZ) {
-               if (ctx->rand_data_valid == DEFAULT_BLK_SZ) {
-                       if (_get_more_prng_bytes(ctx, do_cont_test) < 0) {
-                               memset(buf, 0, nbytes);
-                               err = -EINVAL;
-                               goto done;
-                       }
-               }
+               if (ctx->rand_data_valid == DEFAULT_BLK_SZ &&
+                   _get_more_prng_bytes(ctx, do_cont_test) < 0)
+                       goto reset_memory;
+
                if (ctx->rand_data_valid > 0)
                        goto empty_rbuf;
                memcpy(ptr, ctx->rand_data, DEFAULT_BLK_SZ);
@@ -266,11 +259,16 @@ static int get_prng_bytes(char *buf, size_t nbytes, 
struct prng_context *ctx,
        if (byte_count)
                goto remainder;
 
-done:
+unlock:
        spin_unlock_bh(&ctx->prng_lock);
        dbgprint(KERN_CRIT "returning %d from get_prng_bytes in context %p\n",
                err, ctx);
        return err;
+
+reset_memory:
+       memset(buf, 0, nbytes);
+       err = -EINVAL;
+       goto unlock;
 }
 
 static void free_prng_context(struct prng_context *ctx)
-- 
2.14.2