Attempts to set date with 'date -s' on sparc64 systems running 2.6.15* (maybe previous versions too) hangs the system. Patch -> http://marc.theaimsgroup.com/?l=linux-sparc&m=113861287813463&w=2 This isn't fixed in 2.6.15.2, though it's scheduled upstream. I don't see the need to CC security@ since there's no 2.6 kernel stable on sparc, but feel free to do so if you wish.
http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff_plain;h=cddfc12e2513a4229bad0d05fde2d40a75c3e197;hp=d3ed309a718bc6f79dc485a6d18731990daeee5e
Fixed in gentoo-sources-2.6.15-r3 (genpatches-2.6.15-6)