Kukanganisa kutsva kutsva muEBFF kunobvumidza kupfuura kudzivirirwa paSpecter 4

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Munguva pfupi yapfuura nhau dzakabvarura izvo hurema huviri hwakaonekwa mune linux kernel iyo bvumira kushandisa iyo sisitimu eBPF yekupfuura kudzivirirwa kubva kuSpecter 4 kurwisa (SSB, Yekufungidzira Chitoro Kupfuura). Izvo zvinotaurwa kuti nekushandisa isina rukudzo chirongwa cheBPF, anorwisa anogona kugadzira mamiriro ekufungidzira kuitiswa kweamwe mashandiro uye kuona zvirimo zvekupokana kwenzvimbo dze kernel ndangariro.

Iyo Specter yekurwisa nzira 4 inovimba pakudzorera iyo data rakabatwa mune processor cache mushure mekurasa mhedzisiro yekufungidzira kuisirwa mashandiro kana uchigadzirisa kupindirana kwekuverenga nekunyora mashandiro uchishandisa zvisina kunangana kugadzirisa.

Kana chiitiko chekuverenga chikatevera chiitiko chekunyora, kukanganisa kwenzira yekuverenga kunogona kutove kuzivikanwa nekuda kwekuita kwakafanana .

Kana, mushure mekuverenga kukanganiswa, mharadzano yenzvimbo dzekurangarira yekuverenga nekuverenga ikaonekwa, processor yacho inongorasa mhedzisiro yekuverenga yatowanikwa yekufungidzira uye nekudzokorora kuita uku. Iri basa rinotendera kurairirwa kurairirwa kuti uwane iyo yapfuura kukosha mune imwe nzira apo basa rekuchengetedza richakamirira.

Mushure mekutonga kunze kwekutadza kwekufungidzira kutengeserana, zvisaririra zvekuitwa kwayo zvinoramba zviri mu cache, mushure meizvozvo imwe yemaitiro ekuziva zvirimo mune cache inogona kushandiswa kuitora zvinoenderana nekuongororwa kweshanduko mune cache yekuwana nguva uye yakachengetwa dhata.

Ziva kuti imwe neimwe nhaurwa inogona kushungurudzwa yakazvimiririra kune imwe, ichivimba nayo mukukanganisa kusingawirirani.

MaPoCs akagovaniswa pachivande nevanochengetedza BPF subsystem ku batsira nekugadzirisa kuronga.

Yekutanga kunetseka CVE-2021-35477: inokonzerwa nechikanganiso munzira yekumisikidza chirongwa cheBPF. Kuchengetedza kurwisa kweSpecter 4, iye anotarisa anowedzera wekuwedzera kuraira mushure mezvinogona kunetsa kuchengetedza mashandiro mundangariro, kuchengetera zero zero yekukanganisa maratidziro ebasa rapfuura.

Izvo zvaifungidzirwa kuti zero kunyora kushanda kwaizokurumidza uye kwaizovharidzira kwekufungidzira kuuraya sezvo zvinoenderana chete neBPF stack furema pointer. Asi, muchokwadi, zvaigoneka kugadzira mamiriro umo kuraira kunotungamira mukufungidzira kuuraya kune nguva yekuita pamberi pekudzivirira kuchengetedza oparesheni.

Yechipiri kunetseka CVE-2021-3455: inoenderana nenyaya yekuti kana BPF yekutarisa ikaona inogona kuita njodzi kuchengetedza mashandiro mundangariro, nzvimbo dzisina kuvhurwa dzeBPF stack, yekutanga kunyora mashandiro iyo isina kuchengetedzwa, haina hanya.

Ichi chimiro chinotungamira kune mukana wekuita yekufungidzira kuverenga mashandiro, zvinoenderana neisina kuvhurika ndangariro nzvimbo, usati waita chitoro kuraira. Ndangariro nyowani yeiyo BPF yakagoverwa pasina kutarisa zvirimo izvo zvatove mune yakatarwa ndangariro, uye mudariro chirongwa cheBPF chisati chatanga, pane nzira yekugadzirisa zvirimo munzvimbo yekurangarira, iyo inozogoverwa ku iyo BPF stack.

Mhinduro iripo inoshandisazve nzira dzekudzikamisa kuti dzienderere mberi inokurudzirwa neCPU vatengesi uye inowanikwa mune mainline kernel git yekuchengetedza.

Chekupedzisira, zvinotaurwa kuti vanochengetedza eepf subsystems mune kernel vakawana mukana weiyo yekushandisa prototype iyo inoratidza mukana wekuita kurwisa mukuita.

Matambudziko akagadziriswa nenzira yezvimedu, izvo zvinozobatanidzwa mune inotevera Linux kernel yekuvandudza, saka izvo zvidzoreso zvekusiyana kwakasiyana zvichave kutanga kusvika mumazuva mashoma anotevera.

mabviro: https://www.openwall.com/


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