Commit 5a8e7aea authored Oct 11, 2018 by Cong Wang Committed by David S. Miller Oct 15, 2018

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:  <syzbot+11e05f04c15e03be5254@syzkaller.appspotmail.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David 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);

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