crypto: authenc - Fix zero-length IV crash

As it is if an algorithm with a zero-length IV is used (e.g.,
NULL encryption) with authenc, authenc may generate an SG entry
of length zero, which will trigger a BUG check in the hash layer.

This patch fixes it by skipping the IV SG generation if the IV
size is zero.

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

1 files changed, 15 insertions, 9 deletions

diff --git a/crypto/authenc.c b/crypto/authenc.c
index 40b6e9ec9e3..5793b64c81a 100644
--- a/crypto/authenc.c
+++ b/crypto/authenc.c
@@ -158,16 +158,19 @@ static int crypto_authenc_genicv(struct aead_request *req, u8 *iv,
         dstp = sg_page(dst);
         vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + dst->offset;
 
-        sg_init_table(cipher, 2);
-        sg_set_buf(cipher, iv, ivsize);
-        authenc_chain(cipher, dst, vdst == iv + ivsize);
+        if (ivsize) {
+                sg_init_table(cipher, 2);
+                sg_set_buf(cipher, iv, ivsize);
+                authenc_chain(cipher, dst, vdst == iv + ivsize);
+                dst = cipher;
+        }
 
         cryptlen = req->cryptlen + ivsize;
-        hash = crypto_authenc_hash(req, flags, cipher, cryptlen);
+        hash = crypto_authenc_hash(req, flags, dst, cryptlen);
         if (IS_ERR(hash))
                 return PTR_ERR(hash);
 
-        scatterwalk_map_and_copy(hash, cipher, cryptlen,
+        scatterwalk_map_and_copy(hash, dst, cryptlen,
                                  crypto_aead_authsize(authenc), 1);
         return 0;
 }
@@ -285,11 +288,14 @@ static int crypto_authenc_iverify(struct aead_request *req, u8 *iv,
         srcp = sg_page(src);
         vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + src->offset;
 
-        sg_init_table(cipher, 2);
-        sg_set_buf(cipher, iv, ivsize);
-        authenc_chain(cipher, src, vsrc == iv + ivsize);
+        if (ivsize) {
+                sg_init_table(cipher, 2);
+                sg_set_buf(cipher, iv, ivsize);
+                authenc_chain(cipher, src, vsrc == iv + ivsize);
+                src = cipher;
+        }
 
-        return crypto_authenc_verify(req, cipher, cryptlen + ivsize);
+        return crypto_authenc_verify(req, src, cryptlen + ivsize);
 }
 
 static int crypto_authenc_decrypt(struct aead_request *req)