From: "Jürgen Groß" <jgross@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
Norbert Manthey <nmanthey@amazon.de>,
xen-devel@lists.xenproject.org
Cc: Ian Jackson <iwj@xenproject.org>, 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: Tue, 2 Mar 2021 06:15:26 +0100 [thread overview]
Message-ID: <fc383f00-7bf9-6f2f-54ab-b1e66eed419d@suse.com> (raw)
In-Reply-To: <a840c4fa-148e-7617-20e5-9b286ace2c40@citrix.com>
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On 26.02.21 16:36, Andrew Cooper wrote:
> 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.
I agree. There is no need for this patch.
Juergen
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next prev parent reply other threads:[~2021-03-02 5:15 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
2021-03-02 5:15 ` Jürgen Groß [this message]
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
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