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Commit 5a8e7aea authored by Cong Wang's avatar Cong Wang Committed by David S. Miller
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llc: set SOCK_RCU_FREE in llc_sap_add_socket() 



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: default avatar <syzbot+11e05f04c15e03be5254@syzkaller.appspotmail.com>
Signed-off-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d0f068e5

net/llc/llc_conn.c

+1 −0
Original line number Diff line number Diff line
@@ -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);