netdev - [PATCH v2 net 0/4] dccp/tcp: Fix bhash2 issues related to WARN_ON() in inet_csk_get

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Date:   Wed, 16 Nov 2022 14:28:01 -0800
From:   Kuniyuki Iwashima <kuniyu@...zon.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>
CC:     Arnaldo Carvalho de Melo <acme@...driva.com>,
        Joanne Koong <joannelkoong@...il.com>,
        Martin KaFai Lau <martin.lau@...nel.org>,
        "Mat Martineau" <mathew.j.martineau@...ux.intel.com>,
        "Ziyang Xuan (William)" <william.xuanziyang@...wei.com>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Pengfei Xu <pengfei.xu@...el.com>,
        "Kuniyuki Iwashima" <kuniyu@...zon.com>,
        Kuniyuki Iwashima <kuni1840@...il.com>,
        <netdev@...r.kernel.org>, <dccp@...r.kernel.org>
Subject: [PATCH v2 net 0/4] dccp/tcp: Fix bhash2 issues related to WARN_ON() in inet_csk_get_port().

syzkaller was hitting a WARN_ON() in inet_csk_get_port() in the 4th patch,
which was because we forgot to fix up bhash2 bucket when connect() for a
socket bound to a wildcard address fails in __inet_stream_connect().

There was a similar report [0], but its repro does not fire the WARN_ON() due
to inconsistent error handling.

When connect() for a socket bound to a wildcard address fails, saddr may or
may not be reset depending on where the failure happens.  When we fail in
__inet_stream_connect(), sk->sk_prot->disconnect() resets saddr.  OTOH, in
(dccp|tcp)_v[46]_connect(), if we fail after inet_hash6?_connect(), we
forget to reset saddr.

We fix this inconsistent error handling in the 1st patch, and then we'll
fix the bhash2 WARN_ON() issue.

Note that there is still an issue in that we reset saddr without checking
if there are conflicting sockets in bhash and bhash2, but this should be
another series.

See [1][2] for the previous discussion.

[0]: https://lore.kernel.org/netdev/0000000000003f33bc05dfaf44fe@google.com/
[1]: https://lore.kernel.org/netdev/20221029001249.86337-1-kuniyu@amazon.com/
[2]: https://lore.kernel.org/netdev/20221103172419.20977-1-kuniyu@amazon.com/

Changes:
  v2:
    * Add patch 2-4

  v1: [2]

Kuniyuki Iwashima (4):
  dccp/tcp: Reset saddr on failure after inet6?_hash_connect().
  dccp/tcp: Remove NULL check for prev_saddr in
    inet_bhash2_update_saddr().
  dccp/tcp: Don't update saddr before unlinking sk from the old bucket
  dccp/tcp: Fixup bhash2 bucket when connect() fails.

 include/net/inet_hashtables.h |  3 +-
 net/dccp/ipv4.c               | 23 +++---------
 net/dccp/ipv6.c               | 24 +++---------
 net/dccp/proto.c              |  3 +-
 net/ipv4/af_inet.c            | 11 +-----
 net/ipv4/inet_hashtables.c    | 70 ++++++++++++++++++++++++++++++-----
 net/ipv4/tcp.c                |  3 +-
 net/ipv4/tcp_ipv4.c           | 21 +++--------
 net/ipv6/tcp_ipv6.c           | 20 ++--------
 9 files changed, 85 insertions(+), 93 deletions(-)

-- 
2.30.2