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Re: [PATCH 2/8] store: Detect bad response from xenstored
- To: Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>, "win-pv-devel@xxxxxxxxxxxxxxxxxxxx" <win-pv-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Owen Smith <owen.smith@xxxxxxxxxx>
- Date: Fri, 14 Aug 2026 11:56:01 +0000
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- Delivery-date: Fri, 14 Aug 2026 11:56:09 +0000
- List-id: Developer list for the Windows PV Drivers subproject <win-pv-devel.lists.xenproject.org>
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- Thread-topic: [PATCH 2/8] store: Detect bad response from xenstored
>From: Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>
>Sent: 14 August 2026 11:20 AM
>To: Owen Smith; win-pv-devel@xxxxxxxxxxxxxxxxxxxx
>Subject: Re: [PATCH 2/8] store: Detect bad response from xenstored
>
>On 14/08/2026 12:05, Tu Dinh wrote:
>> On 14/08/2026 09:30, Owen Smith wrote:
>>> Detect when Header.len is larger than allowed, and fail the request.
>>>
>>> Assisted-by: ClaudeCode:claude-opus-4.8
>>> Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
>>
>> Reviewed-by: Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>
>>
>> NB: xencrsh/store.c would likely benefit from the same change.
>>
>>> ---
>>> src/xenbus/store.c | 4 ++++
>>> 1 file changed, 4 insertions(+)
>>>
>>> diff --git a/src/xenbus/store.c b/src/xenbus/store.c
>>> index 503144a..e2a0031 100644
>>> --- a/src/xenbus/store.c
>>> +++ b/src/xenbus/store.c
>>> @@ -519,9 +519,13 @@ StoreReceiveResponse(
>>>
>>> ASSERT(StoreVerifyHeader(&Response->Header));
>>>
>>> + status = STATUS_INVALID_BUFFER_SIZE;
>>> if (Response->Header.len == 0)
>>> goto done;
>>>
>>> + if (Response->Header.len >= XENSTORE_PAYLOAD_MAX)
>
>Never mind, shouldn't this be Response->Header.len > XENSTORE_PAYLOAD_MAX?
>
I was thinking that a length of 4096 should fail, so there is space in the
buffer for a terminating null.
>>> + goto done;
>>> +
>>> Response->Segment[XENBUS_STORE_RESPONSE_PAYLOAD_SEGMENT].Length =
>>> Response->Header.len;
>>> Response->Segment[XENBUS_STORE_RESPONSE_PAYLOAD_SEGMENT].Data =
>>> Response->Data;
>>>
>>
>>
>>
|
