netdev - Re: [Patch net] tipc: check tsk->group in tipc_wait_for

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Message-ID: <2cf006ef-cf00-63fe-d0ca-882f33397598@windriver.com>
Date:   Wed, 12 Dec 2018 19:25:54 +0800
From:   Ying Xue <ying.xue@...driver.com>
To:     Cong Wang <xiyou.wangcong@...il.com>, <netdev@...r.kernel.org>
CC:     Jon Maloy <jon.maloy@...csson.com>
Subject: Re: [Patch net] tipc: check tsk->group in tipc_wait_for_cond()

On 12/12/18 1:43 PM, Cong Wang wrote:
> tipc_wait_for_cond() drops socket lock before going to sleep,
> but tsk->group could be freed right after that release_sock().
> So we have to re-check and reload tsk->group after it wakes up.
> 
> After this patch, tipc_wait_for_cond() returns -ERESTARTSYS when
> tsk->group is NULL, instead of continuing with the assumption of
> a non-NULL tsk->group.
> 
> (It looks like 'dsts' should be re-checked and reloaded too, but
> it is a different bug.)
> 
> Similar for tipc_send_group_unicast() and tipc_send_group_anycast().
> 
> Reported-by: syzbot+10a9db47c3a0e13eb31c@...kaller.appspotmail.com
> Fixes: b7d42635517f ("tipc: introduce flow control for group broadcast messages")
> Fixes: ee106d7f942d ("tipc: introduce group anycast messaging")
> Fixes: 27bd9ec027f3 ("tipc: introduce group unicast messaging")
> Cc: Ying Xue <ying.xue@...driver.com>
> Cc: Jon Maloy <jon.maloy@...csson.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>

Acked-by: Ying Xue <ying.xue@...driver.com>

> ---
>  net/tipc/socket.c | 25 ++++++++++++++-----------
>  1 file changed, 14 insertions(+), 11 deletions(-)
> 
> diff --git a/net/tipc/socket.c b/net/tipc/socket.c
> index e1396fb87779..656940692a44 100644
> --- a/net/tipc/socket.c
> +++ b/net/tipc/socket.c
> @@ -880,7 +880,6 @@ static int tipc_send_group_unicast(struct socket *sock, struct msghdr *m,
>  	DECLARE_SOCKADDR(struct sockaddr_tipc *, dest, m->msg_name);
>  	int blks = tsk_blocks(GROUP_H_SIZE + dlen);
>  	struct tipc_sock *tsk = tipc_sk(sk);
> -	struct tipc_group *grp = tsk->group;
>  	struct net *net = sock_net(sk);
>  	struct tipc_member *mb = NULL;
>  	u32 node, port;
> @@ -894,7 +893,9 @@ static int tipc_send_group_unicast(struct socket *sock, struct msghdr *m,
>  	/* Block or return if destination link or member is congested */
>  	rc = tipc_wait_for_cond(sock, &timeout,
>  				!tipc_dest_find(&tsk->cong_links, node, 0) &&
> -				!tipc_group_cong(grp, node, port, blks, &mb));
> +				tsk->group &&
> +				!tipc_group_cong(tsk->group, node, port, blks,
> +						 &mb));
>  	if (unlikely(rc))
>  		return rc;
>  
> @@ -924,7 +925,6 @@ static int tipc_send_group_anycast(struct socket *sock, struct msghdr *m,
>  	struct tipc_sock *tsk = tipc_sk(sk);
>  	struct list_head *cong_links = &tsk->cong_links;
>  	int blks = tsk_blocks(GROUP_H_SIZE + dlen);
> -	struct tipc_group *grp = tsk->group;
>  	struct tipc_msg *hdr = &tsk->phdr;
>  	struct tipc_member *first = NULL;
>  	struct tipc_member *mbr = NULL;
> @@ -941,9 +941,10 @@ static int tipc_send_group_anycast(struct socket *sock, struct msghdr *m,
>  	type = msg_nametype(hdr);
>  	inst = dest->addr.name.name.instance;
>  	scope = msg_lookup_scope(hdr);
> -	exclude = tipc_group_exclude(grp);
>  
>  	while (++lookups < 4) {
> +		exclude = tipc_group_exclude(tsk->group);
> +
>  		first = NULL;
>  
>  		/* Look for a non-congested destination member, if any */
> @@ -952,7 +953,8 @@ static int tipc_send_group_anycast(struct socket *sock, struct msghdr *m,
>  						 &dstcnt, exclude, false))
>  				return -EHOSTUNREACH;
>  			tipc_dest_pop(&dsts, &node, &port);
> -			cong = tipc_group_cong(grp, node, port, blks, &mbr);
> +			cong = tipc_group_cong(tsk->group, node, port, blks,
> +					       &mbr);
>  			if (!cong)
>  				break;
>  			if (mbr == first)
> @@ -971,7 +973,8 @@ static int tipc_send_group_anycast(struct socket *sock, struct msghdr *m,
>  		/* Block or return if destination link or member is congested */
>  		rc = tipc_wait_for_cond(sock, &timeout,
>  					!tipc_dest_find(cong_links, node, 0) &&
> -					!tipc_group_cong(grp, node, port,
> +					tsk->group &&
> +					!tipc_group_cong(tsk->group, node, port,
>  							 blks, &mbr));
>  		if (unlikely(rc))
>  			return rc;
> @@ -1006,8 +1009,7 @@ static int tipc_send_group_bcast(struct socket *sock, struct msghdr *m,
>  	struct sock *sk = sock->sk;
>  	struct net *net = sock_net(sk);
>  	struct tipc_sock *tsk = tipc_sk(sk);
> -	struct tipc_group *grp = tsk->group;
> -	struct tipc_nlist *dsts = tipc_group_dests(grp);
> +	struct tipc_nlist *dsts = tipc_group_dests(tsk->group);
>  	struct tipc_mc_method *method = &tsk->mc_method;
>  	bool ack = method->mandatory && method->rcast;
>  	int blks = tsk_blocks(MCAST_H_SIZE + dlen);
> @@ -1020,8 +1022,9 @@ static int tipc_send_group_bcast(struct socket *sock, struct msghdr *m,
>  		return -EHOSTUNREACH;
>  
>  	/* Block or return if any destination link or member is congested */
> -	rc = tipc_wait_for_cond(sock, &timeout,	!tsk->cong_link_cnt &&
> -				!tipc_group_bc_cong(grp, blks));
> +	rc = tipc_wait_for_cond(sock, &timeout,
> +				!tsk->cong_link_cnt && tsk->group &&
> +				!tipc_group_bc_cong(tsk->group, blks));
>  	if (unlikely(rc))
>  		return rc;
>  
> @@ -1036,7 +1039,7 @@ static int tipc_send_group_bcast(struct socket *sock, struct msghdr *m,
>  	msg_set_hdr_sz(hdr, GROUP_H_SIZE);
>  	msg_set_destport(hdr, 0);
>  	msg_set_destnode(hdr, 0);
> -	msg_set_grp_bc_seqno(hdr, tipc_group_bc_snd_nxt(grp));
> +	msg_set_grp_bc_seqno(hdr, tipc_group_bc_snd_nxt(tsk->group));
>  
>  	/* Avoid getting stuck with repeated forced replicasts */
>  	msg_set_grp_bc_ack_req(hdr, ack);
>