[PATCH v2 02/15] crypto: morus - fix handling chunked inputs

[Eric Biggers <ebiggers@kernel.org>]

From: Eric Biggers <ebiggers@google.com>

The generic MORUS implementations all fail the improved AEAD tests
because they produce the wrong result with some data layouts.  The issue
is that they assume that if the skcipher_walk API gives 'nbytes' not
aligned to the walksize (a.k.a. walk.stride), then it is the end of the
data.  In fact, this can happen before the end.  Fix them.

Fixes: 396be41f16fd ("crypto: morus - Add generic MORUS AEAD implementations")
Cc: <stable@vger.kernel.org> # v4.18+
Cc: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 crypto/morus1280.c | 13 +++++++------
 crypto/morus640.c  | 13 +++++++------
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/crypto/morus1280.c b/crypto/morus1280.c
index 78ba09db7328c..0747732d5b78a 100644
--- a/crypto/morus1280.c
+++ b/crypto/morus1280.c
@@ -362,18 +362,19 @@ static void crypto_morus1280_process_crypt(struct morus1280_state *state,
 					   const struct morus1280_ops *ops)
 {
 	struct skcipher_walk walk;
-	u8 *dst;
-	const u8 *src;
 
 	ops->skcipher_walk_init(&walk, req, false);
 
 	while (walk.nbytes) {
-		src = walk.src.virt.addr;
-		dst = walk.dst.virt.addr;
+		unsigned int nbytes = walk.nbytes;
 
-		ops->crypt_chunk(state, dst, src, walk.nbytes);
+		if (nbytes < walk.total)
+			nbytes = round_down(nbytes, walk.stride);
 
-		skcipher_walk_done(&walk, 0);
+		ops->crypt_chunk(state, walk.dst.virt.addr, walk.src.virt.addr,
+				 nbytes);
+
+		skcipher_walk_done(&walk, walk.nbytes - nbytes);
 	}
 }
 
diff --git a/crypto/morus640.c b/crypto/morus640.c
index 5cf530139b271..1617a1eb8be13 100644
--- a/crypto/morus640.c
+++ b/crypto/morus640.c
@@ -361,18 +361,19 @@ static void crypto_morus640_process_crypt(struct morus640_state *state,
 					  const struct morus640_ops *ops)
 {
 	struct skcipher_walk walk;
-	u8 *dst;
-	const u8 *src;
 
 	ops->skcipher_walk_init(&walk, req, false);
 
 	while (walk.nbytes) {
-		src = walk.src.virt.addr;
-		dst = walk.dst.virt.addr;
+		unsigned int nbytes = walk.nbytes;
 
-		ops->crypt_chunk(state, dst, src, walk.nbytes);
+		if (nbytes < walk.total)
+			nbytes = round_down(nbytes, walk.stride);
 
-		skcipher_walk_done(&walk, 0);
+		ops->crypt_chunk(state, walk.dst.virt.addr, walk.src.virt.addr,
+				 nbytes);
+
+		skcipher_walk_done(&walk, walk.nbytes - nbytes);
 	}
 }
 
-- 
2.20.1