Not bashing on OpenBSD here, but if anyone has any insights why dhcp would lead to a panic..
I'd like to read that. It's probably interesting and could be a great write-up.
Edit: The mailing list thread has no results so far and suspects a use after free in the network driver? But.. gory details would be nice.
blog author here, like I mentioned in the blog post one of the developers suggested that it might just trigger a re-use of poisoned memory.
OpenBSD (especially on snapshots) enables a lot of 'hostile' development features - poisoning freed memory is one of them. Some of those checks are disabled on releases in order to limit performance degradation. Why could dhcp impact a kernel panic? It boils down to the driver. If my understanding is correct the re0 driver works on the kernel level and uses the mbuf infrastructure for allocating and using memory on the kernel level. The specific memory usage pattern the re0 driver has might lead to the kernel or the driver reusing already freed memory. This is of course just a speculation I have based on the information I included in the blog post and received off list from one developer. It's not confirmed in any way and just an informed guess on the developers part. I think dhcp is just an easier way to trigger the panic as the OS does lock-up on this box when set to static IP even if dhcp was never fired even once (though I don't get dropped to ddb then).
Driver bug probably. Or hardware bug. re isn't especially popular, and there's about about 2 dozen revisions of the chip. Look at about line 679 in the driver. Maybe one of those switch cases is wrong.
Edit: The mailing list thread has no results so far and suspects a use after free in the network driver? But.. gory details would be nice.