From: Jiri Bohac <jbohac@suse•cz>
To: Shan Wei <shanwei@cn•fujitsu.com>
Cc: Jiri Bohac <jbohac@suse•cz>,
linux-sctp@vger•kernel.org, Neil Horman <nhorman@tuxdriver•com>,
Vlad Yasevich <vladislav.yasevich@hp•com>
Subject: Re: [PATCH][RFC] sctp: fix reporting of unknown parameters
Date: Fri, 18 Feb 2011 13:01:42 +0100 [thread overview]
Message-ID: <20110218120142.GA24525@midget.suse.cz> (raw)
In-Reply-To: <4D5E575A.9000905@cn.fujitsu.com>
On Fri, Feb 18, 2011 at 07:26:18PM +0800, Shan Wei wrote:
> Jiri Bohac wrote, at 02/18/2011 07:12 AM:
> > commit 5fa782c2f5ef6c2e4f04d3e228412c9b4a4c8809 re-worked the
> > handling of unknown parameters. sctp_init_cause_fixed() can now
> > return -ENOSPC if there is not enough tailroom in the error
> > chunk skb. When this happens, the error header is not appended to
> > the error chunk. In that case, the payload of the unknown parameter
> > should not be appended either.
> >
> > Signed-off-by: Jiri Bohac <jbohac@suse•cz>
>
> For this case, there is no more tailroom in skb
not always true:
both sctp_init_cause_fixed() and sctp_addto_chunk_fixed() get
passesd WORD_ROUND(ntohs(param.p->length) as the paylen/len
parameter.
sctp_init_cause_fixed() does:
len = sizeof(sctp_errhdr_t) + paylen;
if (skb_tailroom(chunk->skb) < len)
return -ENOSPC;
if paylen is only slightly smaller than the tailroom (by less
than sizeof(sctp_errhdr_t) bytes), -ENOSPEC will be returned and
the header will not be appended to the error chunk.
But later sctp_addto_chunk_fixed() does this check:
if (skb_tailroom(chunk->skb) >= len)
which will pass and the unknown parameter value will be appended
to the error chunk without the error header.
> we send incomplete INIT-ACK chunk. With your patch, this chunk also
> can't info the sender of INIT Chunk which parameter is not unrecognized.
> So maybe this handle is not perfect.
The logic of not reporting unknown parameters for which we don't
have space in the pre-allocated buffer remains unchanged.
--
Jiri Bohac <jbohac@suse•cz>
SUSE Labs, SUSE CZ
next prev parent reply other threads:[~2011-02-18 16:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-17 23:12 [PATCH][RFC] sctp: fix reporting of unknown parameters Jiri Bohac
2011-02-18 11:26 ` Shan Wei
2011-02-18 12:01 ` Jiri Bohac [this message]
2011-02-18 14:43 ` Vladislav Yasevich
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20110218120142.GA24525@midget.suse.cz \
--to=jbohac@suse$(echo .)cz \
--cc=linux-sctp@vger$(echo .)kernel.org \
--cc=nhorman@tuxdriver$(echo .)com \
--cc=shanwei@cn$(echo .)fujitsu.com \
--cc=vladislav.yasevich@hp$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox