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Use pointer to fake bpf_if structure after bpfdetach()
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Authored by ae on Apr 16 2018, 10:49 AM.

Details

Summary
Add dead_bpf_if structure, that should be used as fake bpf_if
during ifnet detach.

Since destroying interface is not atomic operation and due to the
lack of synhronization during destroy, it is possible, that in the
time between bpfdetach() and if_free() some queued on destroying
interface mbuf will be used by ether_input_internal() and bpf_peers_present()
can dereference NULL bpf_if pointer. To protect from this, assign
pointer to empty bpf_if_ext structure instead of NULL pointer after
bpfdetach().

Diff Detail

Repository
rS FreeBSD src repository
Lint
Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

ae created this revision.Apr 16 2018, 10:49 AM
This revision is now accepted and ready to land.Apr 16 2018, 11:05 AM
melifaro accepted this revision.Apr 19 2018, 9:44 PM
melifaro added inline comments.
sys/net/bpf.c
102 ↗(On Diff #41503)

Why do we explicitly zero bif_next?

This revision was automatically updated to reflect the committed changes.