[PATCH AUTOSEL for 4.4 046/167] net: x25: fix one potential use-after-free issue

Sasha Levin
2018-03-19T16:08:32Z

From: linzhang <xiaolou4617@gmail.com>

[ Upstream commit 64df6d525fcff1630098db9238bfd2b3e092d5c1 ]

The function x25_init is not properly unregister related resources
on error handler.It is will result in kernel oops if x25_init init
failed, so add properly unregister call on error handler.

Also, i adjust the coding style and make x25_register_sysctl properly
return failure.

Signed-off-by: linzhang <xiaolou4617@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
include/net/x25.h | 4 ++--
net/x25/af_x25.c | 24 ++++++++++++++++--------
net/x25/sysctl_net_x25.c | 5 ++++-
3 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/include/net/x25.h b/include/net/x25.h
index c383aa4edbf0..6d30a01d281d 100644
--- a/include/net/x25.h
+++ b/include/net/x25.h
@@ -298,10 +298,10 @@ void x25_check_rbuf(struct sock *);

/* sysctl_net_x25.c */
#ifdef CONFIG_SYSCTL
-void x25_register_sysctl(void);
+int x25_register_sysctl(void);
void x25_unregister_sysctl(void);
#else
-static inline void x25_register_sysctl(void) {};
+static inline int x25_register_sysctl(void) { return 0; };
static inline void x25_unregister_sysctl(void) {};
#endif /* CONFIG_SYSCTL */

diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
index a750f330b8dd..c6ab4da4b8e2 100644
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -1794,32 +1794,40 @@ void x25_kill_by_neigh(struct x25_neigh *nb)

static int __init x25_init(void)
{
- int rc = proto_register(&x25_proto, 0);
+ int rc;

- if (rc != 0)
+ rc = proto_register(&x25_proto, 0);
+ if (rc)
goto out;

rc = sock_register(&x25_family_ops);
- if (rc != 0)
+ if (rc)
goto out_proto;

dev_add_pack(&x25_packet_type);

rc = register_netdevice_notifier(&x25_dev_notifier);
- if (rc != 0)
+ if (rc)
goto out_sock;

- pr_info("Linux Version 0.2\n");
+ rc = x25_register_sysctl();
+ if (rc)
+ goto out_dev;

- x25_register_sysctl();
rc = x25_proc_init();
- if (rc != 0)
- goto out_dev;
+ if (rc)
+ goto out_sysctl;
+
+ pr_info("Linux Version 0.2\n");
+
out:
return rc;
+out_sysctl:
+ x25_unregister_sysctl();
out_dev:
unregister_netdevice_notifier(&x25_dev_notifier);
out_sock:
+ dev_remove_pack(&x25_packet_type);
sock_unregister(AF_X25);
out_proto:
proto_unregister(&x25_proto);
diff --git a/net/x25/sysctl_net_x25.c b/net/x25/sysctl_net_x25.c
index 43239527a205..703d46aae7a2 100644
--- a/net/x25/sysctl_net_x25.c
+++ b/net/x25/sysctl_net_x25.c
@@ -73,9 +73,12 @@ static struct ctl_table x25_table[] = {
{ 0, },
};

-void __init x25_register_sysctl(void)
+int __init x25_register_sysctl(void)
{
x25_table_header = register_net_sysctl(&init_net, "net/x25", x25_table);
+ if (!x25_table_header)
+ return -ENOMEM;
+ return 0;
}

void x25_unregister_sysctl(void)
--
2.14.1