crypto: x86/morus - fix handling chunked inputs and MAY_SLEEP

The x86 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.

Also, when the CRYPTO_TFM_REQ_MAY_SLEEP flag is given, they can
incorrectly sleep in the skcipher_walk_*() functions while preemption
has been disabled by kernel_fpu_begin().

Fix these bugs.

Fixes: 56e8e57fc3 ("crypto: morus - Add common SIMD glue code for MORUS")
Cc: <stable@vger.kernel.org> # v4.18+
Cc: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/x86/crypto/morus1280_glue.c

@@ -85,31 +85,20 @@ static void crypto_morus1280_glue_process_ad(
 
 static void crypto_morus1280_glue_process_crypt(struct morus1280_state *state,
 						struct morus1280_ops ops,
-						struct aead_request *req)
+						struct skcipher_walk *walk)
 {
-	struct skcipher_walk walk;
-	u8 *cursor_src, *cursor_dst;
-	unsigned int chunksize, base;
+	while (walk->nbytes >= MORUS1280_BLOCK_SIZE) {
+		ops.crypt_blocks(state, walk->src.virt.addr,
+				 walk->dst.virt.addr,
+				 round_down(walk->nbytes,
+					    MORUS1280_BLOCK_SIZE));
+		skcipher_walk_done(walk, walk->nbytes % MORUS1280_BLOCK_SIZE);
+	}
 
-	ops.skcipher_walk_init(&walk, req, false);
-
-	while (walk.nbytes) {
-		cursor_src = walk.src.virt.addr;
-		cursor_dst = walk.dst.virt.addr;
-		chunksize = walk.nbytes;
-
-		ops.crypt_blocks(state, cursor_src, cursor_dst, chunksize);
-
-		base = chunksize & ~(MORUS1280_BLOCK_SIZE - 1);
-		cursor_src += base;
-		cursor_dst += base;
-		chunksize &= MORUS1280_BLOCK_SIZE - 1;
-
-		if (chunksize > 0)
-			ops.crypt_tail(state, cursor_src, cursor_dst,
-				       chunksize);
-
-		skcipher_walk_done(&walk, 0);
+	if (walk->nbytes) {
+		ops.crypt_tail(state, walk->src.virt.addr, walk->dst.virt.addr,
+			       walk->nbytes);
+		skcipher_walk_done(walk, 0);
 	}
 }
 
@@ -147,12 +136,15 @@ static void crypto_morus1280_glue_crypt(struct aead_request *req,
 	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
 	struct morus1280_ctx *ctx = crypto_aead_ctx(tfm);
 	struct morus1280_state state;
+	struct skcipher_walk walk;
+
+	ops.skcipher_walk_init(&walk, req, true);
 
 	kernel_fpu_begin();
 
 	ctx->ops->init(&state, &ctx->key, req->iv);
 	crypto_morus1280_glue_process_ad(&state, ctx->ops, req->src, req->assoclen);
-	crypto_morus1280_glue_process_crypt(&state, ops, req);
+	crypto_morus1280_glue_process_crypt(&state, ops, &walk);
 	ctx->ops->final(&state, tag_xor, req->assoclen, cryptlen);
 
 	kernel_fpu_end();