Differential D54721

net: on interface detach purge all its routes before detaching protocols
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Authored by glebius on Jan 15 2026, 3:24 AM.

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jhibbits
pouria

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network
transport

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rGf102a1834933: net: on interface detach purge all its routes before detaching protocols

Summary

Otherwise, a forwarding thread may use the interface being detached. This
is a regression from 0d469d23715d, which manifests itself as a reliably
reproducible panic in in6_selecthlim(). Note that there are old bug
reports about such a panic, and I believe this change will not fix them,
as their nature is not due to a screwed up detach sequence, but due to
lack of proper epoch(9) based synchronization between the detach and
forwarding.

Reported & tested by: jhibbits
PR: 292162
Fixes: 0d469d23715d690b863787ebfa51529e1f6a9092

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rG FreeBSD src repository

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Event Timeline

glebius created this revision.Jan 15 2026, 3:24 AM

Herald added subscribers: melifaro, ae, imp. · View Herald TranscriptJan 15 2026, 3:24 AM

glebius requested review of this revision.Jan 15 2026, 3:24 AM

Harbormaster completed remote builds in B69896: Diff 169749.Jan 15 2026, 3:24 AM

glebius added a child revision: D54722: netinet6: embed struct nd_ifinfo into struct in6_ndireq.Jan 15 2026, 3:24 AM

I will test it with openbgp and bird.
I suspect that removing routes before detaching the actual interface might cause unexpected behavior in them.

LGTM
I also tested interface creation and destruction to advertise/withdraw its routes with bird3 (ospf) and openbgpd8.

This revision is now accepted and ready to land.Jan 16 2026, 3:01 PM

Closed by commit rGf102a1834933: net: on interface detach purge all its routes before detaching protocols (authored by glebius). · Explain WhyJan 17 2026, 12:45 AM

This revision was automatically updated to reflect the committed changes.

glebius added a commit: rGf102a1834933: net: on interface detach purge all its routes before detaching protocols.

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sys/

net/

4 lines

Diff 169918

sys/net/if.c

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