crypto: shash - Fix async finup handling of null digest

When shash_ahash_finup encounters a null request, we end up not
calling the underlying final function.  This patch fixes that.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 7 insertions, 2 deletions

diff --git a/crypto/shash.c b/crypto/shash.c
index 834d9d24cdae..7713b520bc98 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -240,12 +240,17 @@ int shash_ahash_finup(struct ahash_request *req, struct shash_desc *desc)
         struct crypto_hash_walk walk;
         int nbytes;
 
-        for (nbytes = crypto_hash_walk_first(req, &walk); nbytes > 0;
-             nbytes = crypto_hash_walk_done(&walk, nbytes))
+        nbytes = crypto_hash_walk_first(req, &walk);
+        if (!nbytes)
+                return crypto_shash_final(desc, req->result);
+
+        do {
                 nbytes = crypto_hash_walk_last(&walk) ?
                          crypto_shash_finup(desc, walk.data, nbytes,
                                             req->result) :
                          crypto_shash_update(desc, walk.data, nbytes);
+                nbytes = crypto_hash_walk_done(&walk, nbytes);
+        } while (nbytes > 0);
 
         return nbytes;
 }