[PATCH 3.16 015/328] crypto: vmac - require a block cipher with 128-bit block size

Ben Hutchings
2018-12-09T22:28:02Z

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")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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))