linux-kernel - [PATCH 4.9 35/35] audit: fix a net reference leak in audit_list_rules

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Message-Id: <20210405085019.983552878@linuxfoundation.org>
Date:   Mon,  5 Apr 2021 10:54:10 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, teroincn@...il.com,
        Richard Guy Briggs <rgb@...hat.com>,
        Paul Moore <paul@...l-moore.com>,
        Wen Yang <wenyang@...ux.alibaba.com>
Subject: [PATCH 4.9 35/35] audit: fix a net reference leak in audit_list_rules_send()

From: Paul Moore <paul@...l-moore.com>

commit 3054d06719079388a543de6adb812638675ad8f5 upstream.

If audit_list_rules_send() fails when trying to create a new thread
to send the rules it also fails to cleanup properly, leaking a
reference to a net structure.  This patch fixes the error patch and
renames audit_send_list() to audit_send_list_thread() to better
match its cousin, audit_send_reply_thread().

Reported-by: teroincn@...il.com
Reviewed-by: Richard Guy Briggs <rgb@...hat.com>
Signed-off-by: Paul Moore <paul@...l-moore.com>
Cc: <stable@...r.kernel.org> # 4.9.x
Signed-off-by: Wen Yang <wenyang@...ux.alibaba.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 kernel/audit.c       |    2 +-
 kernel/audit.h       |    2 +-
 kernel/auditfilter.c |   13 ++++++-------
 3 files changed, 8 insertions(+), 9 deletions(-)

--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -535,7 +535,7 @@ static int kauditd_thread(void *dummy)
 	return 0;
 }
 
-int audit_send_list(void *_dest)
+int audit_send_list_thread(void *_dest)
 {
 	struct audit_netlink_list *dest = _dest;
 	struct sk_buff *skb;
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -245,7 +245,7 @@ struct audit_netlink_list {
 	struct sk_buff_head q;
 };
 
-int audit_send_list(void *);
+int audit_send_list_thread(void *);
 
 struct audit_net {
 	struct sock *nlsk;
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -1139,10 +1139,8 @@ int audit_rule_change(int type, __u32 po
 int audit_list_rules_send(struct sk_buff *request_skb, int seq)
 {
 	u32 portid = NETLINK_CB(request_skb).portid;
-	struct net *net = sock_net(NETLINK_CB(request_skb).sk);
 	struct task_struct *tsk;
 	struct audit_netlink_list *dest;
-	int err = 0;
 
 	/* We can't just spew out the rules here because we might fill
 	 * the available socket buffer space and deadlock waiting for
@@ -1150,10 +1148,10 @@ int audit_list_rules_send(struct sk_buff
 	 * happen if we're actually running in the context of auditctl
 	 * trying to _send_ the stuff */
 
-	dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL);
+	dest = kmalloc(sizeof(*dest), GFP_KERNEL);
 	if (!dest)
 		return -ENOMEM;
-	dest->net = get_net(net);
+	dest->net = get_net(sock_net(NETLINK_CB(request_skb).sk));
 	dest->portid = portid;
 	skb_queue_head_init(&dest->q);
 
@@ -1161,14 +1159,15 @@ int audit_list_rules_send(struct sk_buff
 	audit_list_rules(portid, seq, &dest->q);
 	mutex_unlock(&audit_filter_mutex);
 
-	tsk = kthread_run(audit_send_list, dest, "audit_send_list");
+	tsk = kthread_run(audit_send_list_thread, dest, "audit_send_list");
 	if (IS_ERR(tsk)) {
 		skb_queue_purge(&dest->q);
+		put_net(dest->net);
 		kfree(dest);
-		err = PTR_ERR(tsk);
+		return PTR_ERR(tsk);
 	}
 
-	return err;
+	return 0;
 }
 
 int audit_comparator(u32 left, u32 op, u32 right)