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Subject[PATCH net v3] net: x25: fix one potential use-after-free issue
Date
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>
---

changelog:

v1 -> v2:
* make x25_register_sysctl properly return failure

v2 -> v3:
* keep the same lables as v1
* fix missing semicolon

---
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 c383aa4..6d30a01 100644
--- a/include/net/x25.h
+++ b/include/net/x25.h
@@ -298,10 +298,10 @@ int x25_decode(struct sock *, struct sk_buff *, int *, int *, int *, int *,

/* 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 8b911c2..5a1a98d 100644
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -1791,32 +1791,40 @@ 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 a06dfe1..ba078c8 100644
--- a/net/x25/sysctl_net_x25.c
+++ b/net/x25/sysctl_net_x25.c
@@ -73,9 +73,12 @@
{ },
};

-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)
--
1.8.3.1
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