On Sat, Feb 15, 2025 at 12:11:17AM +0000, Andrew Cooper wrote: > On 15/02/2025 12:07 am, Jennifer Miller wrote: > > On Fri, Feb 14, 2025 at 11:06:50PM +0000, Andrew Cooper wrote: > >> On 13/02/2025 11:24 pm, Jennifer Miller wrote: > >>> On Thu, Feb 13, 2025 at 09:24:18PM +0000, Andrew Cooper wrote: > >>> Still, I hadn't considered misusing readonly/unmapped pages on the GPR > >>> register spill that follows. Could we enforce that the stack pointer we > >>> get > >>> be page aligned to prevent this vector? So that if one were to attempt to > >>> point the stack to readonly or unmapped memory they should be guaranteed > >>> to > >>> double fault? > >> Hmm. > >> > >> Espfix64 does involve #DF recovering from a write to a read-only stack. > >> (This broken corner of x86 is also fixed in FRED. We fixed a *lot* of > >> thing.) > > Interesting, I haven't gotten around to reading into how FRED works, it > > sounds neat. > > Start with > https://docs.google.com/document/d/1hWejnyDkjRRAW-JEsRjA5c9CKLOPc6VKJQsuvODlQEI/edit?usp=sharing > > > Then > https://www.intel.com/content/www/us/en/content-details/779982/flexible-return-and-event-delivery-fred-specification.html > > ~Andrew
Thanks, I'll give those a read! ~Jennifer
