iflib: netmap: fix rsync index overrun
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Authored by vmaffione on Jun 13 2020, 7:50 AM.

Details

Reviewers

gallatin
mmacy
shurd

Group Reviewers

iflib

Commits

rS362810: MFC r362553
rS362553: iflib: netmap: fix rsync index overrun

Summary

In the current iflib_netmap_rxsync, there is nothing that prevents kring->nr_hwtail to overrun kring->nr_hwcur during the descriptor import phase. This may cause errors in netmap applications, such as:

em1 RX0: fail 'head < kring->nr_hwcur || head > kring->nr_hwtail' h 795 c 795 t 282 rh 795 rc 795 rt 282 hc 282 ht 282

Test Plan

Tested on an em device in a VM. After the patch, the problem disappears.

Diff Detail

Repository

rS FreeBSD src repository - subversion

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Lint Not Applicable

Unit

Tests Not Applicable

Event Timeline

vmaffione created this revision.Jun 13 2020, 7:50 AM

Herald added a reviewer: shurd. · View Herald TranscriptJun 13 2020, 7:50 AM

Herald added 1 blocking reviewer(s): iflib. · View Herald Transcript

Herald added subscribers: melifaro, ae, imp. · View Herald Transcript

vmaffione requested review of this revision.Jun 13 2020, 7:50 AM

Harbormaster completed remote builds in B31675: Diff 73059.Jun 13 2020, 7:50 AM

vmaffione mentioned this in D25254: iflib: netmap: add support for partial ring openings.Jun 13 2020, 8:14 AM

I guess no objections here? This is an easy change, that fixes a bug that is very easy to reproduce, and that prevents netmap applications from working for real on iflib.

gallatin accepted this revision.Jun 23 2020, 3:00 PM

This revision is now accepted and ready to land.Jun 23 2020, 3:00 PM

Closed by commit rS362553: iflib: netmap: fix rsync index overrun (authored by vmaffione). · Explain WhyJun 23 2020, 8:24 PM

This revision was automatically updated to reflect the committed changes.

vmaffione added a commit: rS362553: iflib: netmap: fix rsync index overrun.

vmaffione added a commit: rS362810: MFC r362553.Jun 30 2020, 7:34 PM