Appears to be a FFS bug. No repro if the underlying fs is ext2.
The reported size of the null file is also different. If the fs is FFS a user executing this command over SSH will freeze the console (ttyC0), CPU usage climbs to 100%. Regards Lloyd H. Hartzer wrote: > On Wed Oct 22, 2025 at 7:04 PM UTC, Eternity Crew wrote: > > > The following seems sufficient to cause OpenBSD 7.8 to cease all > > normal activities: > > > > $ dd if=/dev/null of=1 bs=1m seek=8000000; (ulimit -t 1; cmp 1 1) > > > > Therefore, this is probably a local DoS. > > > Can you confirm if OpenBSD 7.7 handled this differently? > > -Henrich
