| Message ID | 20181011181513.20203-1-xiyou.wangcong@gmail.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net] llc: set SOCK_RCU_FREE in llc_sap_add_socket() | expand |
From: Cong Wang <xiyou.wangcong@gmail.com> Date: Thu, 11 Oct 2018 11:15:13 -0700 > WHen an llc sock is added into the sk_laddr_hash of an llc_sap, > it is not marked with SOCK_RCU_FREE. > > This causes that the sock could be freed while it is still being > read by __llc_lookup_established() with RCU read lock. sock is > refcounted, but with RCU read lock, nothing prevents the readers > getting a zero refcnt. > > Fix it by setting SOCK_RCU_FREE in llc_sap_add_socket(). > > Reported-by: syzbot+11e05f04c15e03be5254@syzkaller.appspotmail.com > Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Applied and queued up for -stable.
diff --git a/net/llc/llc_conn.c b/net/llc/llc_conn.c index c0ac522b48a1..4ff89cb7c86f 100644 --- a/net/llc/llc_conn.c +++ b/net/llc/llc_conn.c @@ -734,6 +734,7 @@ void llc_sap_add_socket(struct llc_sap *sap, struct sock *sk) llc_sk(sk)->sap = sap; spin_lock_bh(&sap->sk_lock); + sock_set_flag(sk, SOCK_RCU_FREE); sap->sk_count++; sk_nulls_add_node_rcu(sk, laddr_hb); hlist_add_head(&llc->dev_hash_node, dev_hb);
WHen an llc sock is added into the sk_laddr_hash of an llc_sap, it is not marked with SOCK_RCU_FREE. This causes that the sock could be freed while it is still being read by __llc_lookup_established() with RCU read lock. sock is refcounted, but with RCU read lock, nothing prevents the readers getting a zero refcnt. Fix it by setting SOCK_RCU_FREE in llc_sap_add_socket(). Reported-by: syzbot+11e05f04c15e03be5254@syzkaller.appspotmail.com Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> --- net/llc/llc_conn.c | 1 + 1 file changed, 1 insertion(+)