I-Google yethule i-"Half-Double", indlela entsha yokuhlasela ye-RowHammer engashintsha okuqukethwe kwezingcezu ngazinye zememori yokufinyelela engahleliwe (i-DRAM). Ukuhlasela kungenziwa kabusha kwamanye ama-chip e-DRAM anamuhla, abakhiqizi bawo behlise i-geometry yamaseli.
Khumbula ukuthi ukuhlasela kwesigaba se-RowHammer kukuvumela ukuthi uhlanekezele okuqukethwe kwezingcezu zememori ngayinye ngokufunda idatha ngomjikelezo kumaseli enkumbulo angomakhelwane. Njengoba inkumbulo ye-DRAM iwuxhaxha lwamaseli anezinhlangothi ezimbili, ngalinye liqukethe i-capacitor ne-transistor, ukufunda okuqhubekayo kwendawo yenkumbulo efanayo kubangela ukuguquguquka kwamandla kagesi kanye nokudidayo okubangela ukulahlekelwa okuncane kwenkokhiso kumaseli angomakhelwane. Uma umfutho wokufunda uphakeme ngokwanele, khona-ke iseli elingumakhelwane lingase lilahlekelwe inani elikhulu ngokwanele lenkokhelo futhi umjikelezo wokuvuselela olandelayo ngeke ube nesikhathi sokubuyisela isimo sawo sokuqala, okuzoholela ekushintsheni kwenani ledatha egcinwe ku- iseli.
Ukuze kuvikelwe ku-RowHammer, abakhiqizi bama-chip basebenzise indlela ye-TRR (Target Row Refresh) evikela ekonakalisweni kwamaseli emigqeni eseduze. Indlela ye-Half-Double ikuvumela ukuthi udlule lesi sivikelo ngokulawula ukuthi ukuhlanekezela akukhawulelwe emigqeni eseduze futhi kusakazeke kweminye imigqa yenkumbulo, nakuba ngokwezinga elincane. Onjiniyela be-Google babonise ukuthi emigqeni elandelanayo yenkumbulo "A", "B" kanye "no-C", kungenzeka ukuhlasela umugqa "C" ngokufinyelela okunzima kakhulu kumugqa "A" nomsebenzi omncane othinta irowu "B". Ukufinyelela kumugqa "B" phakathi nokuhlasela kwenza kusebenze ukuvuza kwenkokhiso engaqondile futhi kuvumela umugqa "B" ukuthi usetshenziswe njengesithuthi ukudlulisa umphumela we-Rowhammer usuka kumugqa "A" uye "C".
Ngokungafani nokuhlasela kwe-TRRespass, eshintsha amaphutha ekusetshenzisweni okuhlukahlukene kwendlela yokuvimbela inkohlakalo yeseli, ukuhlasela kwe-Half-Double kusekelwe ezintweni ezibonakalayo ze-silicon substrate. I-Half-Double ibonisa ukuthi kungenzeka ukuthi imiphumela eholela ku-Rowhammer iyimpahla yebanga, kunokuhlangana okuqondile kwamaseli. Njengoba i-geometry yeseli kuma-chips esimanje iyancipha, i-radius yethonya lokuhlanekezela nayo iyakhula. Kungenzeka ukuthi umphumela uzobonwa ebangeni lemigqa engaphezu kwemibili.
Kuyaphawuleka ukuthi, kanye nenhlangano ye-JEDEC, kuye kwasungulwa iziphakamiso ezimbalwa ezihlaziya izindlela ezingenzeka zokuvimba ukuhlaselwa okunjalo. Indlela iyadalulwa ngoba i-Google ikholelwa ukuthi ucwaningo lwandisa kakhulu ukuqonda kwethu isenzakalo se-Rowhammer futhi lugqamisa ukubaluleka kwabacwaningi, abakhi bamashipa, nabanye ababambiqhaza abasebenza ndawonye ukuze kuthuthukiswe isixazululo esiphelele sokuvikela sesikhathi eside.
Source: opennet.ru