{"id":99293,"date":"2021-02-28T10:22:45","date_gmt":"2021-02-28T08:22:45","guid":{"rendered":"https:\/\/prohoster.info\/blog\/novosti-interneta\/v-yadro-linux-5-12-prinyata-podsistema-kfence-dlya-vyyavleniya-oshibok-pri-rabote-s-pamyatyu"},"modified":"2021-02-28T10:22:45","modified_gmt":"2021-02-28T08:22:45","slug":"v-yadro-linux-5-12-prinyata-podsistema-kfence-dlya-vyyavleniya-oshibok-pri-rabote-s-pamyatyu","status":"publish","type":"post","link":"https:\/\/prohoster.info\/et\/blog\/novosti-interneta\/v-yadro-linux-5-12-prinyata-podsistema-kfence-dlya-vyyavleniya-oshibok-pri-rabote-s-pamyatyu","title":{"rendered":"Linux 5.12 s\u00fcdamikku on vastu v\u00f5etud KFence alams\u00fcsteem, mis tuvastab m\u00e4lu kasutuse vigu.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Arenduses oleva Linuxi 5.12 s\u00fcdamiku koosseisu on integreeritud KFence (Kernel Electric Fence) mehhanismi teostus, mis kontrollib m\u00e4lu kasutust, tuvastades puhverpiiride \u00fcletamisi, m\u00e4lu juurde p\u00e4\u00e4semist p\u00e4rast vabanemist ning muid sarnase klassi vigu. <\/p>\n

Sarnane funktsionaalsus oli juba olemas tuumas KASAN-i (kernel address sanitizer, kasutab Address Sanitizerit kaasaegsetes gcc-s ja clang-is) ehituse variandina — kuid peamiselt oli see suunatud veaparanduse kasutamiseks. KFence-i alam s\u00fcsteem erineb KASAN-ist suure t\u00f6\u00f6kiirusena, mis v\u00f5imaldab seda funktsiooni kasutada isegi operatsioonis\u00fcsteemide kernelites. <\/p>\n

T\u00f6\u00f6s\u00fcsteemides rakendamine annab v\u00f5imaluse tuvastada m\u00e4lu t\u00f6\u00f6vead, mis ei ilmne testk\u00e4ivitustes ja tulevad esile vaid t\u00f6\u00f6koormuste ajal v\u00f5i pikaajalise t\u00f6\u00f6 (suure \u00fcleminekuaja) korral. Lisaks v\u00f5imaldab KFence'i rakendamine t\u00f6\u00f6s\u00fcsteemides oluliselt suurendada masinate arvu, mis on kaasatud s\u00fcdamiku m\u00e4lu t\u00f6\u00f6 kontrollimisse. <\/p>\n

KFence saavutab minimaalset koormusest s\u00f5ltumatut \u00fclekande kulu, kasutades kaitse lehti (guard pages) m\u00e4luhalduse m\u00e4\u00e4ratud intervallide j\u00e4rgi. P\u00e4rast kaitse intervalli l\u00f5ppemist lisab KFence oma tavap\u00e4rase m\u00e4luhalduss\u00fcsteemi (SLAB v\u00f5i SLUB allocator) kaudu j\u00e4rgmise kaitse lehe KFence objektide basest ja alustab uut ajaloos j\u00e4rgneva ajakonto. Iga KFence objekt paigutatakse eraldi m\u00e4helehe peale ning m\u00e4helehed vasak- ja parempoolses \u00e4\u00e4res moodustavad kaitse lehed, mille suurust valitakse juhuslikult. <\/p>\n

Seega eraldatakse objektidega lehek\u00fcljed kaitse lehek\u00fclgedega, mis on seadistatud genereerima \"page fault\" iga\u00fche juurde p\u00e4\u00e4semisel. Kirjutamise operatsioonide tuvastamiseks m\u00e4lupiiri \u00fcletavas objektide lehek\u00fcljel kasutatakse t\u00e4iendavalt \u0161abloonide p\u00f5hiseid \"punaseid alasid\", mis h\u00f5ivavad m\u00e4lu, mida objektid ei kasuta, ja mis j\u00e4\u00e4b m\u00e4lulehtede suuruse joondamise t\u00f5ttu \u00fcle. —+————+————+————+————+————+— | xxxxxxxxx | O : | xxxxxxxxx | : O | xxxxxxxxx | | xxxxxxxxx | B : | xxxxxxxxx | : B | xxxxxxxxx | | x GUARD x | J : RED- | x GUARD x | RED- : J | x GUARD x | | xxxxxxxxx | E : ZONE | xxxxxxxxx | ZONE : E | xxxxxxxxx | | xxxxxxxxx | C : | xxxxxxxxx | : C | xxxxxxxxx | | xxxxxxxxx | T : | xxxxxxxxx | : T | xxxxxxxxx | —+————+————+————+————+————+— <\/p>\n

Juhul, kui proovite p\u00e4\u00e4seda puhvri piiridest v\u00e4ljapoole, m\u00f5jutab see kaitse lehte, tekitades \"page fault\", mille KFence kinni p\u00fc\u00fcab ja logib tuvastatud probleemi andmed. Vaikimisi KFence ei blokeeri viga ja lihtsalt logib hoiatuse, kuid on olemas seade \"panic_on_warn\", mis v\u00f5imaldab t\u00f5statud vea korral tuua tuuma kriisi (panic) olekusse.
\n
Allikas: opennet.ru<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0412 \u0441\u043e\u0441\u0442\u0430\u0432 \u043d\u0430\u0445\u043e\u0434\u044f\u0449\u0435\u0433\u043e\u0441\u044f \u0432 \u0440\u0430\u0437\u0440\u0430\u0431\u043e\u0442\u043a\u0435 \u044f\u0434\u0440\u0430 Linux 5.12 \u0432\u043a\u043b\u044e\u0447\u0435\u043d\u0430 \u0440\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u044f \u043c\u0435\u0445\u0430\u043d\u0438\u0437\u043c\u0430 KFence (Kernel Electric Fence), \u043a\u043e\u0442\u043e\u0440\u044b\u0439 \u043f\u0440\u043e\u0432\u0435\u0440\u044f\u0435\u0442 \u0440\u0430\u0431\u043e\u0442\u0443 \u0441 \u043f\u0430\u043c\u044f\u0442\u044c\u044e, \u043e\u0442\u043b\u0430\u0432\u043b\u0438\u0432\u0430\u044f \u0432\u044b\u0445\u043e\u0434 \u0437\u0430 \u0433\u0440\u0430\u043d\u0438\u0446\u044b \u0431\u0443\u0444\u0435\u0440\u043e\u0432, \u043e\u0431\u0440\u0430\u0449\u0435\u043d\u0438\u044f \u043a \u043f\u0430\u043c\u044f\u0442\u0438 \u043f\u043e\u0441\u043b\u0435 \u043e\u0441\u0432\u043e\u0431\u043e\u0436\u0434\u0435\u043d\u0438\u044f \u0438 \u0434\u0440\u0443\u0433\u0438\u0435 \u043e\u0448\u0438\u0431\u043a\u0438 \u043f\u043e\u0434\u043e\u0431\u043d\u043e\u0433\u043e \u043a\u043b\u0430\u0441\u0441\u0430. \u041f\u043e\u0434\u043e\u0431\u043d\u0430\u044f \u0444\u0443\u043d\u043a\u0446\u0438\u043e\u043d\u0430\u043b\u044c\u043d\u043e\u0441\u0442\u044c \u0443\u0436\u0435 \u043f\u0440\u0438\u0441\u0443\u0442\u0441\u0442\u0432\u043e\u0432\u0430\u043b\u0430 \u0432 \u044f\u0434\u0440\u0435 \u0432 \u0432\u0438\u0434\u0435 \u043e\u043f\u0446\u0438\u0438 \u0441\u0431\u043e\u0440\u043a\u0438 KASAN (kernel address sanitizer, \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u0435\u0442 Address Sanitizer \u0432 \u0441\u043e\u0432\u0440\u0435\u043c\u0435\u043d\u043d\u044b\u0445 gcc […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-99293","post","type-post","status-publish","format-standard","hentry","category-novosti-interneta"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\n","aioseo_head_json":{"title":"\ud83e\udd47Linux 5.12 tuumas on vastu v\u00f5etud KFence'i s\u00fcsteem m\u00e4lu vigade tuvastamiseks | ProHoster","description":"Arenduses olevasse Linuxi 5.12 tuumasse on lisatud KFence'i (Kernel Electric Fence) mehhanismi rakendus, mis kontrollib m\u00e4lu kasutamist, avastades \u00fcletamised, m\u00e4lu juurdep\u00e4\u00e4sud p\u00e4rast vabastamist ja muud sarnased vead. Sarnane funktsionaalsus oli varasemalt tuumas KASAN (kernel address sanitizer) kogumisvalikuna, mis kasutab Address Sanitizer'i kaasaegsetes gcc'des.","canonical_url":"https:\/\/prohoster.info\/et\/blog\/novosti-interneta\/v-yadro-linux-5-12-prinyata-podsistema-kfence-dlya-vyyavleniya-oshibok-pri-rabote-s-pamyatyu","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"et_EE","og:site_name":"ProHoster | \u041a\u0443\u043f\u0438\u0442\u044c \u043d\u0430\u0434\u0435\u0436\u043d\u044b\u0439 \u0445\u043e\u0441\u0442\u0438\u043d\u0433 \u0434\u043b\u044f \u0441\u0430\u0439\u0442\u043e\u0432 \u0441 \u0437\u0430\u0449\u0438\u0442\u043e\u0439 \u043e\u0442 DDoS, VPS VDS \u0441\u0435\u0440\u0432\u0435\u0440\u044b","og:type":"article","og:title":"\ud83e\udd47\u0412 \u044f\u0434\u0440\u043e Linux 5.12 \u043f\u0440\u0438\u043d\u044f\u0442\u0430 \u043f\u043e\u0434\u0441\u0438\u0441\u0442\u0435\u043c\u0430 KFence \u0434\u043b\u044f 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