Uma exhashazwa, lawa maphutha angavumela abahlaseli ukuthi bathole ukufinyelela okungagunyaziwe kulwazi olubucayi noma ngokuvamile babangele izinkinga.
Muva nje, iqembu labacwaningi abavela eNyuvesi yaseCalifornia eDavis lihlaziye ukuthi kungenzeka yini ukusebenzisa iRowhammer (indlela yokonakala kwe-DRAM bit) ukuze kukhiqizwe izigxivizo zeminwe ezihlukile.
Ngesikhathi sokuhlaziya kwabo, bakhulume ukuthi baqaphele ukuthi uhlobo lokuphazamiseka okubangelwa ukuhlaselwa kweRowhammer luhlukile esimweni ngasinye se-chip ye-DRAM futhi alushintshi ngokuhamba kwesikhathi. Ngenxa yalokho, kwathuthukiswa indlela ye-Centauri, evumela ukuhlonza izinhlelo ezinokunemba okumaphakathi okungu-99,91%.
Ukuze ukhiqize isihlonzi ku-Centauri, mane usebenzise ikhodi imizuzwana embalwa noma imizuzu embalwa. Ngezindleko zokunciphisa ukunemba (kuya ku-0,64), ukuhlonza kungenziwa ngokunciphisa okungu-95% esikhathini kube cishe imizuzwana engu-9.92. Ukunemba okuphezulu kutholakala lapho ukuqinisekiswa kusebenza cishe imizuzu emithathu.
Inqubo yokuhlonza yenziwa ngezigaba ezintathu :
- Kusetshenziswa indlela yeBlacksmith (RowHammer variant) ukuze kunqunywe isu lokuvikela (TRR) elisetshenziswa ku-chip ngokumelene nokuhlanekezelwa kwamaseli enkumbulo.
- Ukwenziwa kwekhodi okuholela ekuhlanekeni
- Ukunqunywa kwesikhundla esihlobene kanye nenombolo yama-capacitor ashintshe inani lenkokhiso.
Isihlonzi sakhiwe ngesisekelo sokwakha ukusatshalaliswa kokuqina kwamathuba okushintsha ukushajwa kwama-capacitor kubhlokhi yememori engu-2-megabyte.
Kulabo kini abangazi ngokuhlaselwa kwekilasi le-RowHammer, kufanele nazi ukuthi kukuvumela ukuthi uhlanekezele okuqukethwe kwezingcezu zememori ngayinye ngokufunda idatha ngomjikelezo kumaseli enkumbulo angomakhelwane.
"I-Centauri iyindlela yokuqala yokubonisa ukukhishwa kwezigxivizo zeminwe eziyingqayizivele nezizinzile ngesilinganiso esikhulu kunazo zonke kusetshenziswa i-Rowhammer ngenkathi inqoba imikhawulo engokoqobo ebekwe uhlelo lokusebenza kanye nokunciphisa i-Rowhammer njenge-TRR"
Njengoba i-DRAM iwuxhaxha lwamaseli anezinhlangothi ezimbili, ngalinye liqukethe i-capacitor kanye ne-transistor, ngokuqhubekayo ukufunda indawo efanayo yememori kuphumela ekuguquguqukeni kwe-voltage kanye nokudidayo okubangela ukulahleka kweshaji kancane. kumaseli angomakhelwane. Uma ukuqina kokufunda kuphezulu, khona-ke iseli elingumakhelwane lingase lilahlekelwe inani elikhulu ngokwanele lenkokhelo futhi umjikelezo wokuvuselela olandelayo ngeke ube nesikhathi sokubuyisela isimo sawo sangempela, okuzobangela ukuguqulwa kwenani ledatha egcinwe esitokisini. .
Inqubo yokukhiqiza ama-chip ayifani, ngakho-ke i-memory chip ngayinye ihlukile ngesakhiwo sayo somzimba ngenxa yokubekezelelana okuhilelekile. Lokhu kuhlukahluka kusho ukuthi ukusatshalaliswa kwamathuba okuphambuka kwama-bit okubangelwa ukuhlaselwa kwe-Rowhammer nakho kuhlukile kwi-module ngayinye yememori eyenziwe, okuyilokho abadali bendlela ye-Centauri abakusebenzisa kabi.
Indlela ye-TRR (Target Row Refresh) esetshenziswa abakhiqizi bememori, evikela ekuhlaselweni yiRowhammer ngokuvimbela ukuphambuka kwamaseli emigqeni eseduze, ayithinti ukunemba kokuhlonza ngendlela yeCentauri.
Ngokwendlela engokoqobo , le ndlela ingasetshenziswa, isibonelo, ukuthola ukushintshwa kwemishini noma ukuhlonza izinhlelo lapho ikhompyutha eyodwa izenza sengathi yimishini ehlukahlukene. Kodwa-ke, akunakwenzeka ukuthi idlulele ngale kocwaningo lwezemfundo, njengoba ukusetshenziswa kwayo kuholela ekugugeni okukhulu kuma-memory chips futhi kungabangela ukungasebenzi kahle kwesofthiwe ngenxa yokuphazamiseka kokuqukethwe kweseli.
Akunakukhishwa ukuthi le ndlela ingashintshwa ukuze isebenze kusiphequluli ukuze kutholakale izivakashi zewebhusayithi, kusetshenziswa ukuqaliswa okulungiselelwe kusengaphambili kweRowhammer kuJavaScript njengesisekelo.
Indlela ihlolwe cishe kumamojula we-DRAM angama-98 (ama-chipset ayi-6 afanayo avela kubakhiqizi ababili). Ukuhlolwa okuphindaphindiwe okwenziwe phakathi kwezinsuku ezingu-10 akuzange kubonise ukwehla kokunemba kokuhlonza.
Okokugcina, uma unesithakazelo sokufunda okwengeziwe, ungathola imininingwane kusixhumanisi esilandelayo.