netdev - [PATCH net-next v4 12/15] ocfs2: Fix use of slab data with sendpage

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Date: Fri, 23 Jun 2023 12:44:22 +0100
From: David Howells <dhowells@...hat.com>
To: netdev@...r.kernel.org
Cc: David Howells <dhowells@...hat.com>,
	Alexander Duyck <alexander.duyck@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Willem de Bruijn <willemdebruijn.kernel@...il.com>,
	David Ahern <dsahern@...nel.org>,
	Matthew Wilcox <willy@...radead.org>,
	Jens Axboe <axboe@...nel.dk>,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Mark Fasheh <mark@...heh.com>,
	Joel Becker <jlbec@...lplan.org>,
	Joseph Qi <joseph.qi@...ux.alibaba.com>,
	ocfs2-devel@....oracle.com
Subject: [PATCH net-next v4 12/15] ocfs2: Fix use of slab data with sendpage

ocfs2 uses kzalloc() to allocate buffers for for o2net_hand, o2net_keep_req
and o2net_keep_resp and then passes these to sendpage.  This isn't really
allowed as the lifetime of slab objects is not controlled by page ref -
though in this case it will probably work.  sendmsg() with MSG_SPLICE_PAGES
will, however, print a warning and give an error.

Fix it to use folio_alloc() instead to allocate a buffer for the handshake
message, keepalive request and reply messages.

Fixes: 98211489d414 ("[PATCH] OCFS2: The Second Oracle Cluster Filesystem")
Signed-off-by: David Howells <dhowells@...hat.com>
cc: Mark Fasheh <mark@...heh.com>
cc: Joel Becker <jlbec@...lplan.org>
cc: Joseph Qi <joseph.qi@...ux.alibaba.com>
cc: "David S. Miller" <davem@...emloft.net>
cc: Eric Dumazet <edumazet@...gle.com>
cc: Jakub Kicinski <kuba@...nel.org>
cc: Paolo Abeni <pabeni@...hat.com>
cc: ocfs2-devel@....oracle.com
cc: netdev@...r.kernel.org
---
 fs/ocfs2/cluster/tcp.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/fs/ocfs2/cluster/tcp.c b/fs/ocfs2/cluster/tcp.c
index aecbd712a00c..929a1133bc18 100644
--- a/fs/ocfs2/cluster/tcp.c
+++ b/fs/ocfs2/cluster/tcp.c
@@ -2087,18 +2087,24 @@ void o2net_stop_listening(struct o2nm_node *node)
 
 int o2net_init(void)
 {
+	struct folio *folio;
+	void *p;
 	unsigned long i;
 
 	o2quo_init();
-
 	o2net_debugfs_init();
 
-	o2net_hand = kzalloc(sizeof(struct o2net_handshake), GFP_KERNEL);
-	o2net_keep_req = kzalloc(sizeof(struct o2net_msg), GFP_KERNEL);
-	o2net_keep_resp = kzalloc(sizeof(struct o2net_msg), GFP_KERNEL);
-	if (!o2net_hand || !o2net_keep_req || !o2net_keep_resp)
+	folio = folio_alloc(GFP_KERNEL | __GFP_ZERO, 0);
+	if (!folio)
 		goto out;
 
+	p = folio_address(folio);
+	o2net_hand = p;
+	p += sizeof(struct o2net_handshake);
+	o2net_keep_req = p;
+	p += sizeof(struct o2net_msg);
+	o2net_keep_resp = p;
+
 	o2net_hand->protocol_version = cpu_to_be64(O2NET_PROTOCOL_VERSION);
 	o2net_hand->connector_id = cpu_to_be64(1);
 
@@ -2124,9 +2130,6 @@ int o2net_init(void)
 	return 0;
 
 out:
-	kfree(o2net_hand);
-	kfree(o2net_keep_req);
-	kfree(o2net_keep_resp);
 	o2net_debugfs_exit();
 	o2quo_exit();
 	return -ENOMEM;
@@ -2135,8 +2138,6 @@ int o2net_init(void)
 void o2net_exit(void)
 {
 	o2quo_exit();
-	kfree(o2net_hand);
-	kfree(o2net_keep_req);
-	kfree(o2net_keep_resp);
 	o2net_debugfs_exit();
+	folio_put(virt_to_folio(o2net_hand));
 }