Re: [PATCH v2 net 4/4] dccp/tcp: Fixup bhash2 bucket when connect() fails.

[Pengfei Xu <pengfei.xu@intel.com>]

Hi Kuniyuki Iwashima,

On 2022-11-16 at 19:20:14 -0800, Kuniyuki Iwashima wrote:
> From:   Pengfei Xu <pengfei.xu@intel.com>
> Date:   Thu, 17 Nov 2022 10:23:01 +0800
> > Hi Kuniyuki Iwashima,
> > 
> > If you consider bisect commit or some other info from below link is useful:
> > "https://lore.kernel.org/lkml/Y2xyHM1fcCkh9AKU@xpf.sh.intel.com/"
> > could you add one more Reported-by tag from me, if no, please ignore the
> > email.
> 
> Hi,
> 
> Thanks for providing a repro and bisecting, and sorry, I didn't subscribe
> LKML and haven't noticed the thread until Stephen forwarded it to the
> netndev mailing list today. [0]
> 
> The issue was brought up for discussion [1] about two weeks before the
> thread.  So, I would recommend that you check netdev first and send a
> report CCing netdev if it is a netwokring stuff.
> 
> The issue is reported by Mat[2], me[1], Ziyang[3], and you, and all of
> them were originally generated by syzkaller.
> 
> If we added all Reported-by tags, they would be:
> 
> Reported-by: syzbot <syzkaller@googlegroups.com>
> Reported-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
> Reported-by: Kuniyuki Iwashima <kuniyu@amazon.com>
> Reported-by: Ziyang Xuan (William) <william.xuanziyang@huawei.com>
> Reported-by: Pengfei Xu <pengfei.xu@intel.com>
> 
> But adding my Reported-by sounds odd, so considering the order, only
> syzbot and Mat ones make sense ?
  Ah, that make sense.

> 
> Anyway, I'll leave the decision to maintainers.
> 
> [0]: https://lore.kernel.org/netdev/20221116085854.0dcfa44d@hermes.local/
> [1]: https://lore.kernel.org/netdev/20221029001249.86337-1-kuniyu@amazon.com/
> [2]: https://lore.kernel.org/netdev/4bae9df4-42c1-85c3-d350-119a151d29@linux.intel.com/
> [3]: https://lore.kernel.org/netdev/4bd122d2-d606-b71e-dbe7-63fa293f0a73@huawei.com/
> 
> Thank you.
> 
> P.S please don't top post at Linux mailing lists :)
Is this suggestion for me, I'm not sure which action I should do if there
is.
If no, please ignore.

Thanks!
BR.

> 
> 
> > 
> > Thanks!
> > BR.
> > 
> > On 2022-11-16 at 14:28:05 -0800, Kuniyuki Iwashima wrote:
> > > If a socket bound to a wildcard address fails to connect(), we
> > > only reset saddr and keep the port.  Then, we have to fix up the
> > > bhash2 bucket; otherwise, the bucket has an inconsistent address
> > > in the list.
> > > 
> > > Also, listen() for such a socket will fire the WARN_ON() in
> > > inet_csk_get_port(). [0]
> > > 
> > > Note that when a system runs out of memory, we give up fixing the
> > > bucket and unlink sk from bhash and bhash2 by inet_put_port().
> > > 
> > > [0]:
> > > WARNING: CPU: 0 PID: 207 at net/ipv4/inet_connection_sock.c:548 inet_csk_get_port (net/ipv4/inet_connection_sock.c:548 (discriminator 1))
> > > Modules linked in:
> > > CPU: 0 PID: 207 Comm: bhash2_prev_rep Not tainted 6.1.0-rc3-00799-gc8421681c845 #63
> > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.amzn2022.0.1 04/01/2014
> > > RIP: 0010:inet_csk_get_port (net/ipv4/inet_connection_sock.c:548 (discriminator 1))
> > > Code: 74 a7 eb 93 48 8b 54 24 18 0f b7 cb 4c 89 e6 4c 89 ff e8 48 b2 ff ff 49 8b 87 18 04 00 00 e9 32 ff ff ff 0f 0b e9 34 ff ff ff <0f> 0b e9 42 ff ff ff 41 8b 7f 50 41 8b 4f 54 89 fe 81 f6 00 00 ff
> > > RSP: 0018:ffffc900003d7e50 EFLAGS: 00010202
> > > RAX: ffff8881047fb500 RBX: 0000000000004e20 RCX: 0000000000000000
> > > RDX: 000000000000000a RSI: 00000000fffffe00 RDI: 00000000ffffffff
> > > RBP: ffffffff8324dc00 R08: 0000000000000001 R09: 0000000000000001
> > > R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
> > > R13: 0000000000000001 R14: 0000000000004e20 R15: ffff8881054e1280
> > > FS:  00007f8ac04dc740(0000) GS:ffff88842fc00000(0000) knlGS:0000000000000000
> > > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > > CR2: 0000000020001540 CR3: 00000001055fa003 CR4: 0000000000770ef0
> > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > > PKRU: 55555554
> > > Call Trace:
> > >  <TASK>
> > >  inet_csk_listen_start (net/ipv4/inet_connection_sock.c:1205)
> > >  inet_listen (net/ipv4/af_inet.c:228)
> > >  __sys_listen (net/socket.c:1810)
> > >  __x64_sys_listen (net/socket.c:1819 net/socket.c:1817 net/socket.c:1817)
> > >  do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
> > >  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)
> > > RIP: 0033:0x7f8ac051de5d
> > > Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 93 af 1b 00 f7 d8 64 89 01 48
> > > RSP: 002b:00007ffc1c177248 EFLAGS: 00000206 ORIG_RAX: 0000000000000032
> > > RAX: ffffffffffffffda RBX: 0000000020001550 RCX: 00007f8ac051de5d
> > > RDX: ffffffffffffff80 RSI: 0000000000000000 RDI: 0000000000000004
> > > RBP: 00007ffc1c177270 R08: 0000000000000018 R09: 0000000000000007
> > > R10: 0000000020001540 R11: 0000000000000206 R12: 00007ffc1c177388
> > > R13: 0000000000401169 R14: 0000000000403e18 R15: 00007f8ac0723000
> > >  </TASK>
> > > 
> > > Fixes: 28044fc1d495 ("net: Add a bhash2 table hashed by port and address")
> > > Reported-by: syzbot <syzkaller@googlegroups.com>
> > > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
> > > ---
> > >  include/net/inet_hashtables.h |  1 +
> > >  net/dccp/ipv4.c               |  3 +--
> > >  net/dccp/ipv6.c               |  3 +--
> > >  net/dccp/proto.c              |  3 +--
> > >  net/ipv4/inet_hashtables.c    | 38 +++++++++++++++++++++++++++++++----
> > >  net/ipv4/tcp.c                |  3 +--
> > >  net/ipv4/tcp_ipv4.c           |  3 +--
> > >  net/ipv6/tcp_ipv6.c           |  3 +--
> > >  8 files changed, 41 insertions(+), 16 deletions(-)
> > > 
> > > diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
> > > index ba06e8b52264..69174093078f 100644
> > > --- a/include/net/inet_hashtables.h
> > > +++ b/include/net/inet_hashtables.h
> > > @@ -282,6 +282,7 @@ inet_bhash2_addr_any_hashbucket(const struct sock *sk, const struct net *net, in
> > >   * rcv_saddr field should already have been updated when this is called.
> > >   */
> > >  int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family);
> > > +void inet_bhash2_reset_saddr(struct sock *sk);
> > >  
> > >  void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
> > >  		    struct inet_bind2_bucket *tb2, unsigned short port);
> > > diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
> > > index 95e376e3b911..b780827f5e0a 100644
> > > --- a/net/dccp/ipv4.c
> > > +++ b/net/dccp/ipv4.c
> > > @@ -143,8 +143,7 @@ int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> > >  	 * This unhashes the socket and releases the local port, if necessary.
> > >  	 */
> > >  	dccp_set_state(sk, DCCP_CLOSED);
> > > -	if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
> > > -		inet_reset_saddr(sk);
> > > +	inet_bhash2_reset_saddr(sk);
> > >  	ip_rt_put(rt);
> > >  	sk->sk_route_caps = 0;
> > >  	inet->inet_dport = 0;
> > > diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
> > > index 94c101ed57a9..602f3432d80b 100644
> > > --- a/net/dccp/ipv6.c
> > > +++ b/net/dccp/ipv6.c
> > > @@ -970,8 +970,7 @@ static int dccp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
> > >  
> > >  late_failure:
> > >  	dccp_set_state(sk, DCCP_CLOSED);
> > > -	if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
> > > -		inet_reset_saddr(sk);
> > > +	inet_bhash2_reset_saddr(sk);
> > >  	__sk_dst_reset(sk);
> > >  failure:
> > >  	inet->inet_dport = 0;
> > > diff --git a/net/dccp/proto.c b/net/dccp/proto.c
> > > index c548ca3e9b0e..85e35c5e8890 100644
> > > --- a/net/dccp/proto.c
> > > +++ b/net/dccp/proto.c
> > > @@ -279,8 +279,7 @@ int dccp_disconnect(struct sock *sk, int flags)
> > >  
> > >  	inet->inet_dport = 0;
> > >  
> > > -	if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
> > > -		inet_reset_saddr(sk);
> > > +	inet_bhash2_reset_saddr(sk);
> > >  
> > >  	sk->sk_shutdown = 0;
> > >  	sock_reset_flag(sk, SOCK_DONE);
> > > diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
> > > index dcb6bc918966..d24a04815f20 100644
> > > --- a/net/ipv4/inet_hashtables.c
> > > +++ b/net/ipv4/inet_hashtables.c
> > > @@ -871,7 +871,7 @@ static void inet_update_saddr(struct sock *sk, void *saddr, int family)
> > >  	}
> > >  }
> > >  
> > > -int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family)
> > > +static int __inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family, bool reset)
> > >  {
> > >  	struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk);
> > >  	struct inet_bind2_bucket *tb2, *new_tb2;
> > > @@ -882,7 +882,11 @@ int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family)
> > >  
> > >  	if (!inet_csk(sk)->icsk_bind2_hash) {
> > >  		/* Not bind()ed before. */
> > > -		inet_update_saddr(sk, saddr, family);
> > > +		if (reset)
> > > +			inet_reset_saddr(sk);
> > > +		else
> > > +			inet_update_saddr(sk, saddr, family);
> > > +
> > >  		return 0;
> > >  	}
> > >  
> > > @@ -891,8 +895,19 @@ int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family)
> > >  	 * allocation fails.
> > >  	 */
> > >  	new_tb2 = kmem_cache_alloc(hinfo->bind2_bucket_cachep, GFP_ATOMIC);
> > > -	if (!new_tb2)
> > > +	if (!new_tb2) {
> > > +		if (reset) {
> > > +			/* The (INADDR_ANY, port) bucket might have already been
> > > +			 * freed, then we cannot fixup icsk_bind2_hash, so we give
> > > +			 * up and unlink sk from bhash/bhash2 not to fire WARN_ON()
> > > +			 * in inet_csk_get_port().
> > > +			 */
> > > +			inet_put_port(sk);
> > > +			inet_reset_saddr(sk);
> > > +		}
> > > +
> > >  		return -ENOMEM;
> > > +	}
> > >  
> > >  	/* Unlink first not to show the wrong address for other threads. */
> > >  	head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
> > > @@ -902,7 +917,10 @@ int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family)
> > >  	inet_bind2_bucket_destroy(hinfo->bind2_bucket_cachep, inet_csk(sk)->icsk_bind2_hash);
> > >  	spin_unlock_bh(&head2->lock);
> > >  
> > > -	inet_update_saddr(sk, saddr, family);
> > > +	if (reset)
> > > +		inet_reset_saddr(sk);
> > > +	else
> > > +		inet_update_saddr(sk, saddr, family);
> > >  
> > >  	/* Update bhash2 bucket. */
> > >  	head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
> > > @@ -922,8 +940,20 @@ int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family)
> > >  
> > >  	return 0;
> > >  }
> > > +
> > > +int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family)
> > > +{
> > > +	return __inet_bhash2_update_saddr(sk, saddr, family, false);
> > > +}
> > >  EXPORT_SYMBOL_GPL(inet_bhash2_update_saddr);
> > >  
> > > +void inet_bhash2_reset_saddr(struct sock *sk)
> > > +{
> > > +	if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
> > > +		__inet_bhash2_update_saddr(sk, NULL, 0, true);
> > > +}
> > > +EXPORT_SYMBOL_GPL(inet_bhash2_reset_saddr);
> > > +
> > >  /* RFC 6056 3.3.4.  Algorithm 4: Double-Hash Port Selection Algorithm
> > >   * Note that we use 32bit integers (vs RFC 'short integers')
> > >   * because 2^16 is not a multiple of num_ephemeral and this
> > > diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> > > index 54836a6b81d6..4f2205756cfe 100644
> > > --- a/net/ipv4/tcp.c
> > > +++ b/net/ipv4/tcp.c
> > > @@ -3114,8 +3114,7 @@ int tcp_disconnect(struct sock *sk, int flags)
> > >  
> > >  	inet->inet_dport = 0;
> > >  
> > > -	if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
> > > -		inet_reset_saddr(sk);
> > > +	inet_bhash2_reset_saddr(sk);
> > >  
> > >  	sk->sk_shutdown = 0;
> > >  	sock_reset_flag(sk, SOCK_DONE);
> > > diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> > > index 23dd7e9df2d5..da46357f501b 100644
> > > --- a/net/ipv4/tcp_ipv4.c
> > > +++ b/net/ipv4/tcp_ipv4.c
> > > @@ -331,8 +331,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> > >  	 * if necessary.
> > >  	 */
> > >  	tcp_set_state(sk, TCP_CLOSE);
> > > -	if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
> > > -		inet_reset_saddr(sk);
> > > +	inet_bhash2_reset_saddr(sk);
> > >  	ip_rt_put(rt);
> > >  	sk->sk_route_caps = 0;
> > >  	inet->inet_dport = 0;
> > > diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
> > > index 2f3ca3190d26..f0548dbcabd2 100644
> > > --- a/net/ipv6/tcp_ipv6.c
> > > +++ b/net/ipv6/tcp_ipv6.c
> > > @@ -346,8 +346,7 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
> > >  
> > >  late_failure:
> > >  	tcp_set_state(sk, TCP_CLOSE);
> > > -	if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
> > > -		inet_reset_saddr(sk);
> > > +	inet_bhash2_reset_saddr(sk);
> > >  failure:
> > >  	inet->inet_dport = 0;
> > >  	sk->sk_route_caps = 0;
> > > -- 
> > > 2.30.2