From 6e050778c5d08a97d5d98f7cb62bc503e872615c Mon Sep 17 00:00:00 2001
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Fri, 14 Dec 2007 00:44:11 +0800
Subject: [PATCH] [CRYPTO] scatterwalk: Handle zero nbytes in
 scatterwalk_map_and_copy

It's better to return silently than crash and burn when someone feeds us
a zero length.  In particular the null digest algorithm when used as part
of authenc will do that to us.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
 crypto/scatterwalk.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
index 297e19d13c4e..9aeeb52004a5 100644
--- a/crypto/scatterwalk.c
+++ b/crypto/scatterwalk.c
@@ -105,6 +105,9 @@ void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
 	struct scatter_walk walk;
 	unsigned int offset = 0;
 
+	if (!nbytes)
+		return;
+
 	for (;;) {
 		scatterwalk_start(&walk, sg);