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Differential D58734

bpf: don't move an already-detached bpf_if in bpf_vmove
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Authored by seuros on Sat, Aug 8, 7:47 PM.
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Subscribers
ae
imp
melifaro

Details

Reviewers
glebius
zlei
adrian
Summary

if_vmove() unconditionally called bpf_vmove(), even after bpfdetach()
has replaced if_bpf with the dead_bpf_if sentinel. bpf_vmove() then
treated the sentinel as a live bpf_if and corrupted its list linkage,
panicking under QUEUE_MACRO_DEBUG on epair vnet teardown.

panic: bpf_vmove: Bad link elm ... next->prev != elm

Exported the sentinel via bpf_dead_if() so bpf_vmove() can recognize it
and skip it.

MFC: 1 week

Test Plan
  1. Create a VNET jail and give it one peer of an epair(4):

    jail -c name=t vnet persist ifconfig epair0 create ifconfig epair0a vnet t
  1. Inside the jail, bring the interface up and generate some traffic (anything that attaches bpf works dhclient, tcpdump -i epair0a, ect.)
  1. Destroy the jail:

    jail -r t

I was configuring forgejo, blackship and a test runner.. Happens in current and 15.1

Diff Detail

Repository
rG FreeBSD src repository
Lint
Lint Passed
Unit
No Test Coverage
Build Status
Buildable 75462
Build 72345: arc lint + arc unit

Event Timeline

seuros created this revision.Sat, Aug 8, 7:47 PM
Herald added subscribers: melifaro, ae, imp. · View Herald TranscriptSat, Aug 8, 7:47 PM
seuros requested review of this revision.Sat, Aug 8, 7:47 PM
Harbormaster completed remote builds in B75462: Diff 183697.Sat, Aug 8, 7:47 PM
glebius added a comment.Sat, Aug 8, 7:51 PM

How can I reproduce the problem?

seuros edited the test plan for this revision. (Show Details)Sat, Aug 8, 8:05 PM
seuros added a comment.EditedSat, Aug 8, 8:15 PM

I was writing the instructions in the test plan.

I have a blackship manifest that reproduce it 100%

Btw the system has WITNESS , INVARIANTS enabled.

seuros edited the summary of this revision. (Show Details)Sat, Aug 8, 8:15 PM

Revision Contents
Changeset List

PathSize
sys/
net/
1 line
12 lines
3 lines

Diff 183697

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sys/net/bpf.h

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sys/net/bpf.c

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sys/net/bpf_ifnet.c

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