Document:
02781: Resolve VIRTIO-137: used len field requirements not documented clearly

Draft (A preliminary unapproved sketch, outline, or version.)

Details

Submitted By Mr. Michael S. Tsirkin on 2015-04-01 4:06 pm UTC

Publication Type

None at this time.

Group / Folder

OASIS Virtual I/O Device (VIRTIO) TC / System Ballot Results

Modified by

Not modified.

Copy

This document is not a copy.

Technical Contact

None at this time.

Download Count

370

Download Agreement

None at this time.

Description

Please vote Yes if you agree with all of the following. If you disagree, please vote No. If you don't have an opinion, please vote Abstain. I move that: The TC agrees to resolve the following specification issue: VIRTIO-137: used len field requirements not documented clearly -------------------------------------- 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). -------------------------------------- The TC accepts the following proposed changes to the specification: -------------------------------------- https://lists.oasis-open.org/archives/virtio-comment/201503/msg00007.html -------------------------------------- The TC agrees to include the above change(s) in specification version(s) "virtio 1.0 cs03", and future versions of the specification. -------------------------------------- Reminder: A Voting Member must be active in a TC to maintain voting rights. As the Virtio TC has adopted a standing rule to conduct business only by electronic ballot, without Meetings, a Voting Member who fails to cast a ballot in two consecutive Work Product Ballots loses his or her voting rights at the close of the second ballot missed. --------------------------------------