[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>
diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
index 297e19d1..9aeeb52 100644
--- a/crypto/scatterwalk.c
+++ b/crypto/scatterwalk.c
@@ -105,6 +105,9 @@
struct scatter_walk walk;
unsigned int offset = 0;
+ if (!nbytes)
+ return;
+
for (;;) {
scatterwalk_start(&walk, sg);