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	llc: fix NULL pointer deref for SOCK_ZAPPED
For SOCK_ZAPPED socket, we don't need to care about llc->sap,
so we should just skip these refcount functions in this case.
Fixes: f7e4367268 ("llc: hold llc_sap before release_sock()")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
			
			
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					 1 changed files with 12 additions and 9 deletions
				
			
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			@ -189,7 +189,6 @@ static int llc_ui_release(struct socket *sock)
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{
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	struct sock *sk = sock->sk;
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	struct llc_sock *llc;
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	struct llc_sap *sap;
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	if (unlikely(sk == NULL))
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		goto out;
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			@ -200,15 +199,19 @@ static int llc_ui_release(struct socket *sock)
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		llc->laddr.lsap, llc->daddr.lsap);
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	if (!llc_send_disc(sk))
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		llc_ui_wait_for_disc(sk, sk->sk_rcvtimeo);
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	sap = llc->sap;
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	/* Hold this for release_sock(), so that llc_backlog_rcv() could still
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	 * use it.
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	if (!sock_flag(sk, SOCK_ZAPPED)) {
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		struct llc_sap *sap = llc->sap;
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		/* Hold this for release_sock(), so that llc_backlog_rcv()
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		 * could still use it.
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		 */
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		llc_sap_hold(sap);
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	if (!sock_flag(sk, SOCK_ZAPPED))
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		llc_sap_remove_socket(llc->sap, sk);
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		release_sock(sk);
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		llc_sap_put(sap);
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	} else {
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		release_sock(sk);
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	}
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	if (llc->dev)
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		dev_put(llc->dev);
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	sock_put(sk);
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