tipc: use the right skb in tipc_sk_fill_sock_diag()

Commit 4b2e6877b879 ("tipc: Fix namespace violation in tipc_sk_fill_sock_diag")
tried to fix the crash but failed, the crash is still 100% reproducible
with it.

In tipc_sk_fill_sock_diag(), skb is the diag dump we are filling, it is not
correct to retrieve its NETLINK_CB(), instead, like other protocol diag,
we should use NETLINK_CB(cb->skb).sk here.

Reported-by: <syzbot+326e587eff1074657718@syzkaller.appspotmail.com>
Fixes: 4b2e6877b879 ("tipc: Fix namespace violation in tipc_sk_fill_sock_diag")
Fixes: c30b70deb5f4 (tipc: implement socket diagnostics for AF_TIPC)
Cc: GhantaKrishnamurthy MohanKrishna <mohan.krishna.ghanta.krishnamurthy@ericsson.com>
Cc: Jon Maloy <jon.maloy@ericsson.com>
Cc: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 6 insertions, 6 deletions

diff --git a/net/tipc/diag.c b/net/tipc/diag.c
index 46d9cd62f781..aaabb0b776dd 100644
--- a/net/tipc/diag.c
+++ b/net/tipc/diag.c
@@ -59,7 +59,7 @@ static int __tipc_add_sock_diag(struct sk_buff *skb,
         if (!nlh)
                 return -EMSGSIZE;
 
-        err = tipc_sk_fill_sock_diag(skb, tsk, req->tidiag_states,
+        err = tipc_sk_fill_sock_diag(skb, cb, tsk, req->tidiag_states,
                                      __tipc_diag_gen_cookie);
         if (err)
                 return err;
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index cee6674a3bf4..1fd1c8b5ce03 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -3257,8 +3257,8 @@ out:
 }
 EXPORT_SYMBOL(tipc_nl_sk_walk);
 
-int tipc_sk_fill_sock_diag(struct sk_buff *skb, struct tipc_sock *tsk,
-                           u32 sk_filter_state,
+int tipc_sk_fill_sock_diag(struct sk_buff *skb, struct netlink_callback *cb,
+                           struct tipc_sock *tsk, u32 sk_filter_state,
                            u64 (*tipc_diag_gen_cookie)(struct sock *sk))
 {
         struct sock *sk = &tsk->sk;
@@ -3280,7 +3280,7 @@ int tipc_sk_fill_sock_diag(struct sk_buff *skb, struct tipc_sock *tsk,
             nla_put_u32(skb, TIPC_NLA_SOCK_TIPC_STATE, (u32)sk->sk_state) ||
             nla_put_u32(skb, TIPC_NLA_SOCK_INO, sock_i_ino(sk)) ||
             nla_put_u32(skb, TIPC_NLA_SOCK_UID,
-                        from_kuid_munged(sk_user_ns(NETLINK_CB(skb).sk),
+                        from_kuid_munged(sk_user_ns(NETLINK_CB(cb->skb).sk),
                                          sock_i_uid(sk))) ||
             nla_put_u64_64bit(skb, TIPC_NLA_SOCK_COOKIE,
                               tipc_diag_gen_cookie(sk),
diff --git a/net/tipc/socket.h b/net/tipc/socket.h
index aae3fd4cd06c..aff9b2ae5a1f 100644
--- a/net/tipc/socket.h
+++ b/net/tipc/socket.h
@@ -61,8 +61,8 @@ int tipc_sk_rht_init(struct net *net);
 void tipc_sk_rht_destroy(struct net *net);
 int tipc_nl_sk_dump(struct sk_buff *skb, struct netlink_callback *cb);
 int tipc_nl_publ_dump(struct sk_buff *skb, struct netlink_callback *cb);
-int tipc_sk_fill_sock_diag(struct sk_buff *skb, struct tipc_sock *tsk,
-                           u32 sk_filter_state,
+int tipc_sk_fill_sock_diag(struct sk_buff *skb, struct netlink_callback *cb,
+                           struct tipc_sock *tsk, u32 sk_filter_state,
                            u64 (*tipc_diag_gen_cookie)(struct sock *sk));
 int tipc_nl_sk_walk(struct sk_buff *skb, struct netlink_callback *cb,
                     int (*skb_handler)(struct sk_buff *skb,