Google yayambitsa "Half-Double", njira yatsopano yowukira ya RowHammer yomwe ingasinthe zomwe zili mumtundu wa dynamic random access memory (DRAM). Kuwukiraku kutha kupangidwanso pazida zamakono za DRAM, zomwe opanga achepetsa ma geometry a cell.
Kumbukirani kuti kuukira m'kalasi la RowHammer kumakupatsani mwayi wosokoneza zomwe zili m'makumbukidwe amunthu powerenga mozungulira deta kuchokera kumaselo okumbukira oyandikana nawo. Popeza kukumbukira kwa DRAM ndi ma cell amitundu iwiri, iliyonse imakhala ndi capacitor ndi transistor, kuwerengera mosalekeza kwa dera lomwelo la kukumbukira kumabweretsa kusinthasintha kwamagetsi ndi zolakwika zomwe zimapangitsa kutayika pang'ono kwa ma cell oyandikana nawo. Ngati kuchuluka kwa kuwerenga kuli kokwanira, ndiye kuti selo loyandikana nalo likhoza kutaya ndalama zokwanira ndipo kusinthika kotsatira sikudzakhala ndi nthawi yobwezeretsa chikhalidwe chake choyambirira, chomwe chidzatsogolera kusintha kwa mtengo wa deta yosungidwa mu selo.
Pofuna kuteteza ku RowHammer, opanga ma chip agwiritsa ntchito njira ya TRR (Target Row Refresh) yomwe imateteza ku ziphuphu zama cell omwe ali m'mizere yoyandikana. Njira ya Half-Double imakulolani kuti mudutse chitetezo ichi poyendetsa kuti zosokoneza sizimangokhala mizere yoyandikana ndikufalikira ku mizere ina ya kukumbukira, ngakhale pang'ono. Akatswiri opanga Google awonetsa kuti pamzere wotsatizana wa kukumbukira "A", "B" ndi "C", ndizotheka kuwukira mzere "C" wokhala ndi mwayi wolemetsa kwambiri pamzere "A" komanso zochitika zazing'ono zomwe zimakhudza mzere "B". Kufikira mzere "B" pakuwukira kumayambitsa kutayikira kopanda mzere ndikulola kuti mzere "B" ugwiritsidwe ntchito ngati mayendedwe kusamutsa mawonekedwe a Rowhammer kuchokera pamzere "A" kupita ku "C".
Mosiyana ndi kuwukira kwa TRRespass, komwe kumapangitsa zolakwika pakukhazikitsa kosiyanasiyana kwa njira zopewera ziphuphu zama cell, kuukira kwa Half-Double kumatengera mawonekedwe a gawo lapansi la silicon. Half-Double ikuwonetsa kuti zikutheka kuti zotsatira zomwe zimatsogolera ku Rowhammer ndi katundu wamtunda, osati kugwirizanitsa mwachindunji kwa maselo. Pamene ma geometry a cell mu tchipisi tamakono akucheperachepera, ma radius osokonekera amakulanso. N'zotheka kuti zotsatira zake zidzawoneka pamtunda wa mizere yoposa iwiri.
Zikudziwika kuti, pamodzi ndi bungwe la JEDEC, malingaliro angapo apangidwa kusanthula njira zomwe zingatheke kuti aletse ziwonetserozi. Njirayi ikuwululidwa chifukwa Google ikukhulupirira kuti kafukufukuyu akukulitsa kumvetsetsa kwathu kwa zochitika za Rowhammer ndikuwunikira kufunikira kwa ofufuza, opanga ma chipmaker, ndi ena ogwira nawo ntchito omwe akugwira ntchito limodzi kuti apange njira yothetsera chitetezo chokwanira cha nthawi yaitali.
Source: opennet.ru