From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Norbert Manthey <nmanthey@amazon.de>, <xen-devel@lists.xenproject.org>
Cc: Ian Jackson <iwj@xenproject.org>, Juergen Gross <jgross@suse.com>,
Wei Liu <wl@xen.org>, Julien Grall <jgrall@amazon.co.uk>,
Michael Kurth <mku@amazon.de>
Subject: Re: [PATCH XENSTORE v1 06/10] xenstored: handle port reads correctly
Date: Fri, 26 Feb 2021 15:36:57 +0000 [thread overview]
Message-ID: <a840c4fa-148e-7617-20e5-9b286ace2c40@citrix.com> (raw)
In-Reply-To: <20210226144144.9252-7-nmanthey@amazon.de>
On 26/02/2021 14:41, Norbert Manthey wrote:
> The read value could be larger than a signed 32bit integer. As -1 is
> used as error value, we should not rely on using the full 32 bits.
> Hence, when reading the port number, we should make sure we only return
> valid values.
>
> This change sanity checks the input.
> The issue is that the value for the port is
> 1. transmitted as a string, with a fixed amount of digits.
> 2. Next, this string is parsed by a function that can deal with strings
> representing 64bit integers
> 3. A 64bit integer is returned, and will be truncated to it's lower
> 32bits, resulting in a wrong port number (in case the sender of the
> string decides to craft a suitable 64bit value).
>
> The value is typically provided by the kernel, which has this value hard
> coded in the proper range. As we use the function strtoul, non-digit
> character are considered as end of the input, and hence do not require
> checking. Therefore, this change only covers the corner case to make
> sure we stay in the 32 bit range.
>
> This bug was discovered and resolved using Coverity Static Analysis
> Security Testing (SAST) by Synopsys, Inc.
>
> Signed-off-by: Norbert Manthey <nmanthey@amazon.de>
> Reviewed-by: Thomas Friebel <friebelt@amazon.de>
> Reviewed-by: Julien Grall <jgrall@amazon.co.uk>
Port numbers are currently limited at 2^17, with easy extension to 2^29
(iirc), but the entire event channel infrastructure would have to
undergo another redesign to get beyond that.
I think we can reasonably make an ABI statement saying that a port
number will never exceed 2^31. This is already pseudo-encoded in the
evtchn_port_or_error_t mouthful.
~Andrew
next prev parent reply other threads:[~2021-02-26 15:37 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-26 14:41 [PATCH XENSTORE v1 00/10] Code analysis fixes Norbert Manthey
2021-02-26 14:41 ` [PATCH XENSTORE v1 01/10] xenstore: add missing NULL check Norbert Manthey
2021-03-02 5:07 ` Jürgen Groß
2021-03-03 16:07 ` Ian Jackson
2021-02-26 14:41 ` [PATCH XENSTORE v1 02/10] xenstore: fix print format string Norbert Manthey
2021-03-02 5:07 ` Jürgen Groß
2021-03-03 16:08 ` Ian Jackson
2021-02-26 14:41 ` [PATCH XENSTORE v1 03/10] xenstore: check formats of trace Norbert Manthey
2021-03-02 5:08 ` Jürgen Groß
2021-03-03 16:08 ` Ian Jackson
2021-02-26 14:41 ` [PATCH XENSTORE v1 04/10] xenstore_client: handle memory on error Norbert Manthey
2021-03-02 5:08 ` Jürgen Groß
2021-03-03 16:10 ` Ian Jackson
2021-02-26 14:41 ` [PATCH XENSTORE v1 05/10] xenstore: handle daemon creation errors Norbert Manthey
2021-03-02 5:08 ` Jürgen Groß
2021-03-03 16:10 ` Ian Jackson
2021-02-26 14:41 ` [PATCH XENSTORE v1 06/10] xenstored: handle port reads correctly Norbert Manthey
2021-02-26 15:36 ` Andrew Cooper [this message]
2021-03-02 5:15 ` Jürgen Groß
2021-03-02 7:48 ` Norbert Manthey
2021-03-02 8:12 ` Jürgen Groß
2021-02-26 14:41 ` [PATCH XENSTORE v1 07/10] xenstore: handle do_mkdir and do_rm failure Norbert Manthey
2021-03-02 5:09 ` Jürgen Groß
2021-03-03 16:11 ` Ian Jackson
2021-02-26 14:41 ` [PATCH XENSTORE v1 08/10] xenstore: add missing NULL check Norbert Manthey
2021-03-02 5:10 ` Jürgen Groß
2021-03-03 16:11 ` Ian Jackson
2021-02-26 14:41 ` [PATCH XENSTORE v1 09/10] xs: handle daemon socket error Norbert Manthey
2021-03-02 5:10 ` Jürgen Groß
2021-03-03 16:13 ` Ian Jackson
2021-03-04 14:58 ` Norbert Manthey
2021-03-04 15:04 ` Ian Jackson
2021-02-26 14:41 ` [PATCH XENSTORE v1 10/10] xs: add error handling Norbert Manthey
2021-02-26 14:53 ` Julien Grall
2021-02-26 15:26 ` Norbert Manthey
2021-03-02 5:11 ` Jürgen Groß
2021-03-03 16:13 ` Ian Jackson
2021-03-01 18:01 ` [for-4.15] Re: [PATCH XENSTORE v1 00/10] Code analysis fixes Julien Grall
2021-03-01 19:39 ` Andrew Cooper
2021-03-02 10:04 ` Julien Grall
2021-03-03 18:45 ` Julien Grall
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=a840c4fa-148e-7617-20e5-9b286ace2c40@citrix.com \
--to=andrew.cooper3@citrix.com \
--cc=iwj@xenproject.org \
--cc=jgrall@amazon.co.uk \
--cc=jgross@suse.com \
--cc=mku@amazon.de \
--cc=nmanthey@amazon.de \
--cc=wl@xen.org \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
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;
as well as URLs for NNTP newsgroup(s).