OASIS Mailing List ArchivesView the OASIS mailing list archive below
or browse/search using MarkMail.

 


Help: OASIS Mailing Lists Help | MarkMail Help

virtio message

[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]


Subject: [OASIS Issue Tracker] (VIRTIO-137) used len field requirements not documented clearly


Rusty Russell created VIRTIO-137:
------------------------------------

             Summary: used len field requirements not documented clearly
                 Key: VIRTIO-137
                 URL: https://issues.oasis-open.org/browse/VIRTIO-137
             Project: OASIS Virtual I/O Device (VIRTIO) TC
          Issue Type: Bug
    Affects Versions: virtio 1.0 cs02, virtio 1.0 csprd03
         Environment: Rusty Russell <rusty@au1.ibm.com>
            Reporter: Rusty Russell
            Assignee: Rusty Russell


When debugging qemu (which gets this wrong), I noted that the used ring's len field is only documented as follows:

  \field{len} the total of bytes written into the buffer.

Followed by a (presumably non-normative) note:
  ...  is extremely useful for drivers using untrusted buffers: if you do not know exactly how much has been written by the device, you usually have to zero the buffer to ensure no data leakage occurs.

There is thus an implication that 'len' indicates the amount which was definitely overwritten by the device, but it should be clearly spelled out (such as what happens in the error case where the device may not know how much was actually overwritten).




--
This message was sent by Atlassian JIRA
(v6.2.2#6258)


[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]