[PATCH v4 net 0/4] dccp/tcp: Fix bhash2 issues related to WARN_ON() in inet_csk_get_port().

[PATCH v4 net 0/4] dccp/tcp: Fix bhash2 issues related to WARN_ON() in inet_csk_get_port().

[Kuniyuki Iwashima]

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/
[3]: https://lore.kernel.org/netdev/20221118081906.053d5231@kernel.org/T/#m00aafedb29ff0b55d5e67aef0252ef1baaf4b6ee


Changes:
  v4:
    * Patch 3
      * Narrow down the bhash lock section (Joanne Koong)

  v3: https://lore.kernel.org/netdev/20221118205839.14312-1-kuniyu@amazon.com/
    * Patch 3
      * Update saddr under the bhash's lock
      * Correct Fixes tag
      * Change #ifdef in inet_update_saddr() along the recent
        discussion [3]

  v2: https://lore.kernel.org/netdev/20221116222805.64734-1-kuniyu@amazon.com/
    * 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: Update saddr under bhash's lock.
  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    | 84 ++++++++++++++++++++++++++++++-----
 net/ipv4/tcp.c                |  3 +-
 net/ipv4/tcp_ipv4.c           | 21 +++------
 net/ipv6/tcp_ipv6.c           | 20 ++-------
 9 files changed, 96 insertions(+), 96 deletions(-)

-- 
2.30.2

Re: [PATCH v4 net 0/4] dccp/tcp: Fix bhash2 issues related to WARN_ON() in inet_csk_get_port().

[Eric Dumazet]

On Fri, Nov 18, 2022 at 5:49 PM Kuniyuki Iwashima <kuniyu@amazon.com> wrote:
>
> 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/
> [3]: https://lore.kernel.org/netdev/20221118081906.053d5231@kernel.org/T/#m00aafedb29ff0b55d5e67aef0252ef1baaf4b6ee
>
>
> Changes:
>   v4:
>     * Patch 3
>       * Narrow down the bhash lock section (Joanne Koong)
>
>   v3: https://lore.kernel.org/netdev/20221118205839.14312-1-kuniyu@amazon.com/
>     * Patch 3
>       * Update saddr under the bhash's lock
>       * Correct Fixes tag
>       * Change #ifdef in inet_update_saddr() along the recent
>         discussion [3]
>
>   v2: https://lore.kernel.org/netdev/20221116222805.64734-1-kuniyu@amazon.com/
>     * 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: Update saddr under bhash's lock.
>   dccp/tcp: Fixup bhash2 bucket when connect() fails.

SGTM, thanks !

Reviewed-by: Eric Dumazet <edumazet@google.com>

Re: [PATCH v4 net 0/4] dccp/tcp: Fix bhash2 issues related to WARN_ON() in inet_csk_get_port().

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Fri, 18 Nov 2022 17:49:10 -0800 you wrote:
> 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.
> 
> [...]

Here is the summary with links:
  - [v4,net,1/4] dccp/tcp: Reset saddr on failure after inet6?_hash_connect().
    https://git.kernel.org/netdev/net/c/77934dc6db0d
  - [v4,net,2/4] dccp/tcp: Remove NULL check for prev_saddr in inet_bhash2_update_saddr().
    https://git.kernel.org/netdev/net/c/8acdad37cd13
  - [v4,net,3/4] dccp/tcp: Update saddr under bhash's lock.
    https://git.kernel.org/netdev/net/c/8c5dae4c1a49
  - [v4,net,4/4] dccp/tcp: Fixup bhash2 bucket when connect() fails.
    https://git.kernel.org/netdev/net/c/e0833d1fedb0

You are awesome, thank you!
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