Vulnerabilidad en kernel de Linux (CVE-2021-47379)

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: blk-cgroup: corrige UAF capturando el bloqueo de blkcg antes de destruir blkg pd KASAN informa un informe de use after free al realizar una prueba fuzz: [693354.104835] ======= ==================================================== ========= [693354.105094] ERROR: KASAN: use after free en bfq_io_set_weight_legacy+0xd3/0x160 [693354.105336] Lectura de tamaño 4 en la dirección ffff888be0a35664 por tarea sh/1453338 [693354.10560 7] CPU: 41 PID: 1453338 Comm: sh Kdump: cargado No contaminado 4.18.0-147 [693354.105610] Nombre de hardware: Huawei 2288H V5/BC11SPSCB0, BIOS 0.81 02/07/2018 [693354.105612] Seguimiento de llamadas: [693354.105621] +0xf1/0x19b [693354.105626] ? show_regs_print_info+0x5/0x5 [693354.105634] ? imprimirk+0x9c/0xc3 [693354.105638] ? cpumask_weight+0x1f/0x1f [693354.105648] print_address_description+0x70/0x360 [693354.105654] kasan_report+0x1b2/0x330 [693354.105659] ? bfq_io_set_weight_legacy+0xd3/0x160 [693354.105665] ? bfq_io_set_weight_legacy+0xd3/0x160 [693354.105670] bfq_io_set_weight_legacy+0xd3/0x160 [693354.105675] ? bfq_cpd_init+0x20/0x20 [693354.105683] cgroup_file_write+0x3aa/0x510 [693354.105693] ? ___slab_alloc+0x507/0x540 [693354.105698] ? cgroup_file_poll+0x60/0x60 [693354.105702] ? 0xffffffff89600000 [693354.105708] ? usercopy_abort+0x90/0x90 [693354.105716] ? mutex_lock+0xef/0x180 [693354.105726] kernfs_fop_write+0x1ab/0x280 [693354.105732] ? cgroup_file_poll+0x60/0x60 [693354.105738] vfs_write+0xe7/0x230 [693354.105744] ksys_write+0xb0/0x140 [693354.105749] ? __ia32_sys_read+0x50/0x50 [693354.105760] do_syscall_64+0x112/0x370 [693354.105766] ? syscall_return_slowpath+0x260/0x260 [693354.105772]? do_page_fault+0x9b/0x270 [693354.105779] ? prepare_exit_to_usermode+0xf9/0x1a0 [693354.105784] ? enter_from_user_mode+0x30/0x30 [693354.105793] Entry_SYSCALL_64_after_hwframe+0x65/0xca [693354.105875] Asignado por la tarea 1453337: [693354.106001] kasan_kmalloc+0xa0/0xd0 [693354. 106006] kmem_cache_alloc_node_trace+0x108/0x220 [693354.106010] bfq_pd_alloc+0x96/0x120 [693354.106015] blkcg_activate_policy+ 0x1b7/0x2b0 [693354.106020] bfq_create_group_hierarchy+0x1e/0x80 [693354.106026] bfq_init_queue+0x678/0x8c0 [693354.106031] blk_mq_init_sched+0x1f8/0x460 [693354.106037] elevator_switch_mq+0xe1/0x240 [693354.106041] elevator_switch+0x25/0x40 [693354.106045] elv_iosched_store+0x1a1/ 0x230 [693354.106049] queue_attr_store+0x78/0xb0 [693354.106053] kernfs_fop_write+0x1ab/0x280 [693354.106056] vfs_write+0xe7/0x230 [693354.106060] s_write+0xb0/0x140 [693354.106064] do_syscall_64+0x112/0x370 [693354.106069] Entry_SYSCALL_64_after_hwframe+0x65/0xca [ 693354.106114] Liberado por la tarea 1453336: [693354.106225] __kasan_slab_free+0x130/0x180 [693354.106229] kfree+0x90/0x1b0 [693354.106233] blkcg_deactivate_policy+0x12 c/0x220 [693354.106238] bfq_exit_queue+0xf5/0x110 [693354.106241] blk_mq_exit_sched+0x104/0x130 [693354.106245] __elevator_exit+0x45/0x60 [693354.106249] elevator_switch_mq+0xd6/0x240 [693354.106253] interruptor_elevador+0x25/0x40 [693354.106257] elv_iosched_store+0x1a1/0x230 .106261] queue_attr_store+0x78/0xb0 [693354.106264] kernfs_fop_write+0x1ab/0x280 [693354.106268] vfs_write+ 0xe7/0x230 [693354.106271] ksys_write+0xb0/0x140 [693354.106275] do_syscall_64+0x112/0x370 [693354.106280] Entry_SYSCALL_64_after_hwframe+0x65/0xca [69335 4.106329] La dirección con errores pertenece al objeto en ffff888be0a35580 que pertenece al caché kmalloc-1k de tamaño 1024 [693354.106736] La dirección con errores se encuentra a 228 bytes dentro de la región de 1024 bytes [ffff888be0a35580, ffff888be0a35980) [693354.107114] La dirección con errores pertenece a la página: [693354.107273] página:ffffea002f828c00 1 recuento de mapas: 0 mapeo: ffff888107c17080 índice: 0x0 Compound_mapcount: 0 [693354.107606] banderas: 0x17ffffc0008100(slab|head) [693354.107760] raw: 0017ffffc0008100 ffffea002fcbc808 ffffea0030bd3a08 ffff888107c17080 3354.108020] r ---truncado---