crypto: algif_hash - Handle initial af_alg_make_sg error correctly

When the first call to af_alg_make_sg fails, we may return garbage
instead of the real error.  This patch fixes it by setting the error
if "copied" is zero.

Based on a patch by Jesper Juhl.

Reported-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 3 insertions, 1 deletions

diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c
index 62122a1a2f7a..ef5356cd280a 100644
--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -68,8 +68,10 @@ static int hash_sendmsg(struct kiocb *unused, struct socket *sock,
                         int newlen;
 
                         newlen = af_alg_make_sg(&ctx->sgl, from, len, 0);
-                        if (newlen < 0)
+                        if (newlen < 0) {
+                                err = copied ? 0 : newlen;
                                 goto unlock;
+                        }
 
                         ahash_request_set_crypt(&ctx->req, ctx->sgl.sg, NULL,
                                                 newlen);