[PATCH 4.17 13/21] crypto: vmac - require a block cipher with 128-bit block size

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Biggers <ebiggers@google.com>

commit 73bf20ef3df262026c3470241ae4ac8196943ffa upstream.

The VMAC template assumes the block cipher has a 128-bit block size, but
it failed to check for that.  Thus it was possible to instantiate it
using a 64-bit block size cipher, e.g. "vmac(cast5)", causing
uninitialized memory to be used.

Add the needed check when instantiating the template.

Fixes: f1939f7c5645 ("crypto: vmac - New hash algorithm for intel_txt support")
Cc: <stable@vger.kernel.org> # v2.6.32+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 crypto/vmac.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/crypto/vmac.c
+++ b/crypto/vmac.c
@@ -655,6 +655,10 @@ static int vmac_create(struct crypto_tem
 	if (IS_ERR(alg))
 		return PTR_ERR(alg);
 
+	err = -EINVAL;
+	if (alg->cra_blocksize != 16)
+		goto out_put_alg;
+
 	inst = shash_alloc_instance("vmac", alg);
 	err = PTR_ERR(inst);
 	if (IS_ERR(inst))