-==<XTBA>==-

geohot: well actually it's pretty simple
geohot: i allocate a piece of memory
geohot: using map_htab and write_htab, you can figure out the real address
of the memory
geohot: which is a big win, and something the hv shouldn't allow
geohot: i fill the htab with tons of entries pointing to that piece of
memory
geohot: and since i allocated it, i can map it read/write
geohot: then, i deallocate the memory
geohot: all those entries are set to invalid
geohot: well while it's setting entries invalid, i glitch the memory control
bus
geohot: the cache writeback misses the memory
geohot: and i have entries allowing r/w to a piece of memory the hypervisor
thinks is deallocated
geohot: then i create a virtual segment with the htab overlapping that piece
of memory i have
geohot: write an entry into the virtual segment htab allowing r/w to the main
segment htab
geohot: switch to virtual segment
geohot: write to main segment htab a r/w mapping of itself
geohot: switch back
geohot: PWNED
geohot: and would work if memory were encrypted or had ECC
geohot: the way i actually glitch the memory bus is really funny
geohot: i have a button on my FPGA board
geohot: that pulses low for 40ns
geohot: i set up the htab with the tons of entries
geohot: and spam press the button
geohot: right after i send the deallocate call

en effet j'avais suivi son job au niveau du deplombage de l'Iphone, et je savais qu'il etait sur ce projet, franchement ça commence a devenir sympa tout ça, si le chargement de homebrew par HDD peut devenir réalisable.....