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>

diff --git a/crypto/authenc.c b/crypto/authenc.c
index 40b6e9e..5793b64 100644 (file)
--- 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)