rxrpc: Fix using alignmask being zero for __page_frag_alloc_align()

rxrpc_alloc_data_txbuf() may be called with data_align being
zero in none_alloc_txbuf() and rxkad_alloc_txbuf(), data_align
is supposed to be an order-based alignment value, but zero is
not a valid order-based alignment value, and '~(data_align - 1)'
doesn't result in a valid mask-based alignment value for
__page_frag_alloc_align().

Fix it by passing a valid order-based alignment value in
none_alloc_txbuf() and rxkad_alloc_txbuf().

Also use page_frag_alloc_align() expecting an order-based
alignment value in rxrpc_alloc_data_txbuf() to avoid doing the
alignment converting operation and to catch possible invalid
alignment value in the future. Remove the 'if (data_align)'
checking too, as it is always true for a valid order-based
alignment value.

Fixes: 6b253646 ("rxrpc: Fix use of changed alignment param to page_frag_alloc_align()")
Fixes: 49489bb0 ("rxrpc: Do zerocopy using MSG_SPLICE_PAGES and page frags")
CC: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Acked-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20240428111640.27306-1-linyunsheng@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/rxrpc/insecure.c

@@ -19,7 +19,7 @@ static int none_init_connection_security(struct rxrpc_connection *conn,
  */
 static struct rxrpc_txbuf *none_alloc_txbuf(struct rxrpc_call *call, size_t remain, gfp_t gfp)
 {
-	return rxrpc_alloc_data_txbuf(call, min_t(size_t, remain, RXRPC_JUMBO_DATALEN), 0, gfp);
+	return rxrpc_alloc_data_txbuf(call, min_t(size_t, remain, RXRPC_JUMBO_DATALEN), 1, gfp);
 }
 
 static int none_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)

net/rxrpc/rxkad.c

@@ -155,7 +155,7 @@ static struct rxrpc_txbuf *rxkad_alloc_txbuf(struct rxrpc_call *call, size_t rem
 	switch (call->conn->security_level) {
 	default:
 		space = min_t(size_t, remain, RXRPC_JUMBO_DATALEN);
-		return rxrpc_alloc_data_txbuf(call, space, 0, gfp);
+		return rxrpc_alloc_data_txbuf(call, space, 1, gfp);
 	case RXRPC_SECURITY_AUTH:
 		shdr = sizeof(struct rxkad_level1_hdr);
 		break;

net/rxrpc/txbuf.c

@@ -21,20 +21,20 @@ struct rxrpc_txbuf *rxrpc_alloc_data_txbuf(struct rxrpc_call *call, size_t data_
 {
 	struct rxrpc_wire_header *whdr;
 	struct rxrpc_txbuf *txb;
-	size_t total, hoff = 0;
+	size_t total, hoff;
 	void *buf;
 
 	txb = kmalloc(sizeof(*txb), gfp);
 	if (!txb)
 		return NULL;
 
-	if (data_align)
-		hoff = round_up(sizeof(*whdr), data_align) - sizeof(*whdr);
+	hoff = round_up(sizeof(*whdr), data_align) - sizeof(*whdr);
 	total = hoff + sizeof(*whdr) + data_size;
 
+	data_align = umax(data_align, L1_CACHE_BYTES);
 	mutex_lock(&call->conn->tx_data_alloc_lock);
-	buf = __page_frag_alloc_align(&call->conn->tx_data_alloc, total, gfp,
-				      ~(data_align - 1) & ~(L1_CACHE_BYTES - 1));
+	buf = page_frag_alloc_align(&call->conn->tx_data_alloc, total, gfp,
+				    data_align);
 	mutex_unlock(&call->conn->tx_data_alloc_lock);
 	if (!buf) {
 		kfree(txb);