linux-kernel - [PATCH net] rxrpc: Fix using alignmask being zero for __page_frag_alloc

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Date: Mon, 22 Apr 2024 19:55:40 +0800
From: Yunsheng Lin <linyunsheng@...wei.com>
To: <davem@...emloft.net>, <kuba@...nel.org>, <pabeni@...hat.com>
CC: <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Yunsheng Lin
	<linyunsheng@...wei.com>, David Howells <dhowells@...hat.com>, Alexander
 Duyck <alexander.duyck@...il.com>, Marc Dionne <marc.dionne@...istor.com>,
	Eric Dumazet <edumazet@...gle.com>, <linux-afs@...ts.infradead.org>
Subject: [PATCH net] 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: 6b2536462fd4 ("rxrpc: Fix use of changed alignment param to page_frag_alloc_align()")
Fixes: 49489bb03a50 ("rxrpc: Do zerocopy using MSG_SPLICE_PAGES and page frags")
CC: David Howells <dhowells@...hat.com>
CC: Alexander Duyck <alexander.duyck@...il.com>
Signed-off-by: Yunsheng Lin <linyunsheng@...wei.com>
---
 net/rxrpc/insecure.c |  2 +-
 net/rxrpc/rxkad.c    |  2 +-
 net/rxrpc/txbuf.c    | 10 +++++-----
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/net/rxrpc/insecure.c b/net/rxrpc/insecure.c
index f2701068ed9e..b52b75a0fdac 100644
--- a/net/rxrpc/insecure.c
+++ b/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), 1U, gfp);
 }
 
 static int none_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
diff --git a/net/rxrpc/rxkad.c b/net/rxrpc/rxkad.c
index f1a68270862d..c48e93a26b2a 100644
--- a/net/rxrpc/rxkad.c
+++ b/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, 1U, gfp);
 	case RXRPC_SECURITY_AUTH:
 		shdr = sizeof(struct rxkad_level1_hdr);
 		break;
diff --git a/net/rxrpc/txbuf.c b/net/rxrpc/txbuf.c
index e0679658d9de..994d6582d5e2 100644
--- a/net/rxrpc/txbuf.c
+++ b/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 = max_t(size_t, 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);
-- 
2.33.0