Vulnerabilidad en kernel de Linux (CVE-2024-39474)

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: mm/vmalloc: corrige vmalloc que puede devolver nulo si se llama con __GFP_NOFAIL commit a421ef303008 ("mm: permitir asignaciones !GFP_KERNEL para kvmalloc") incluye soporte para __GFP_NOFAIL, pero presenta un conflicto con el commit dd544141b9eb ("vmalloc: retroceda cuando la tarea actual sea eliminada por OOM"). Un posible escenario es el siguiente: procesar-a __vmalloc_node_range(GFP_KERNEL | __GFP_NOFAIL) __vmalloc_area_node() vm_area_alloc_pages() --> oom-killer envía SIGKILL al proceso-a if (fatal_signal_pending(current)) break; --> devolver NULO; Para solucionar este problema, no marque fatal_signal_pending() en vm_area_alloc_pages() si __GFP_NOFAIL está configurado. Este problema ocurrió durante la PRUEBA DE OPLUS KASAN. A continuación se muestra parte del registro -> oom-killer envía señal para procesar [65731.222840] [T1308] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0,global_oom,task_memcg=/apps/ uid_10198,task=gs.intelligence,pid=32454,uid=10198 [65731.259685] [T32454] Rastreo de llamadas: [65731.259698] [T32454] dump_backtrace+0xf4/0x118 [65731.259734] [T32454] pila+0x18/0x24 [65731.259756] [ T32454] dump_stack_lvl+0x60/0x7c [65731.259781] [T32454] dump_stack+0x18/0x38 [65731.259800] [T32454] mrdump_common_die+0x250/0x39c [mrdump] [65731.259936] T32454] ipanic_die+0x20/0x34 [mrdump] [65731.260019] [ T32454] atomic_notifier_call_chain+0xb4/0xfc [65731.260047] [T32454] notify_die+0x114/0x198 [65731.260073] [T32454] die+0xf4/0x5b4 [65731.260098] [T32454] kernel_fault+0x80/0x98 [65731.260124] [T32454] __do_kernel_fault+0x160/ 0x2a8 [65731.260146] [T32454] do_bad_area+0x68/0x148 [65731.260174] [T32454] do_mem_abort+0x151c/0x1b34 [65731.260204] [T32454] x5c [65731.260227] [T32454] el1h_64_sync_handler+0x54/0x90 [65731.260248] [T32454 ] el1h_64_sync+0x68/0x6c [65731.260269] [T32454] z_erofs_decompress_queue+0x7f0/0x2258 --> be->decompressed_pages = kvcalloc(be->nr_pages, sizeof(struct page *), GFP_KERNEL | __GFP_NOFAIL); pánico del kernel por desreferencia del puntero NULL. erofs supone que kvmalloc con __GFP_NOFAIL nunca devuelve NULL. [65731.260293] [T32454] z_erofs_runqueue+0xf30/0x104c [65731.260314] [T32454] z_erofs_readahead+0x4f0/0x968 [65731.260339] [T32454] c [65731.260364] [T32454] page_cache_ra_unbounded+0x874/0xf30 [65731.260388] [T32454] page_cache_ra_order+0x24c/0x714 [65731.260411] [T32454] filemap_fault+0xbf0/0x1a74 [65731.260437] [T32454] __do_fault+0xd0/0x33c [65731.260462] [T32454] mm_fault+0xf74/0x3fe0 [65731.260486] [T32454] do_mem_abort+0x54c/0x1b34 [ 65731.260509] [T32454] el0_da+0x44/0x94 [65731.260531] [T32454] el0t_64_sync_handler+0x98/0xb4 [65731.260553] [T32454] el0t_64_sync+0x198/0x19c