netdev - Re: [PATCH net 1/6] sctp: remove the unnecessary state check in sctp_outq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Sat, 10 Sep 2016 00:03:53 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     Neil Horman <nhorman@...driver.com>
Cc:     network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org,
        davem <davem@...emloft.net>,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Vlad Yasevich <vyasevich@...il.com>, daniel@...earbox.net
Subject: Re: [PATCH net 1/6] sctp: remove the unnecessary state check in sctp_outq_tail

> I don't know, I still don't feel safe about it.  I agree the socket lock keeps
> the state from changing during a single transmission, which makes the use case
> you are focused on correct.
ok, :-)

>
> That said, have you considered the retransmit case?  That is to say, if you
> queue and flush the outq, and some packets fail delivery, and in the time
> between the intial send and the expiration of the RTX timer (during which the
> socket lock will have been released), an event may occur which changes the
> transport state, which will then be ignored with your patch.
Sorry, I'm not sure if I got it.

You mean "during which changes q->asoc->state", right ?

This patch removes the check of q->asoc->state in sctp_outq_tail().

sctp_outq_tail() is called for data only in:
sctp_primitive_SEND -> sctp_do_sm -> sctp_cmd_send_msg ->
sctp_cmd_interpreter -> sctp_cmd_send_msg() -> sctp_outq_tail()

before calling sctp_primitive_SEND, hold sock lock first.
then sctp_primitive_SEND choose FUNC according:

#define TYPE_SCTP_PRIMITIVE_SEND  {
....

if asoc->state is unavailable, FUNC can't be sctp_cmd_send_msg,
but sctp_sf_error_closed/sctp_sf_error_shutdown,  sctp_outq_tail
can't be called, either.
I mean sctp_primitive_SEND do the same check for asoc->state
already actually.

so the code in sctp_outq_tail is redundant actually.




>
> Neil
>