Vulnerabilidad en kernel de Linux (CVE-2021-47097)

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: Entrada: elantech - arregla la pila fuera del acceso limitado en elantech_change_report_id() El parámetro de matriz[] en elantech_change_report_id() debe tener al menos 3 bytes, porque elantech_read_reg_params() está llamando a ps2_command( ) con PSMOUSE_CMD_GETINFO, que accederá a 3 bytes desde param[], pero está definido en la pila como una matriz de 2 bytes, por lo tanto, aquí tenemos un posible acceso fuera de los límites a la pila, también confirmado por KASAN: [6.512374 ] ERROR: KASAN: pila fuera de los límites en __ps2_command+0x372/0x7e0 [6.512397] Lectura del tamaño 1 en la dirección ffff8881024d77c2 por tarea kworker/2:1/118 [6.512416] CPU: 2 PID: 118 Comm: kworker/ 2:1 No contaminado 5.13.0-22-generic #22+arighi20211110 [6.512428] Nombre de hardware: LENOVO 20T8000QGE/20T8000QGE, BIOS R1AET32W (1.08) 14/08/2020 [6.512436] Cola de trabajo: events_long serio_handle_even t [6.512453] Seguimiento de llamadas: [6.512462] show_stack+0x52/0x58 [6.512474] dump_stack+0xa1/0xd3 [6.512487] print_address_description.constprop.0+0x1d/0x140 [6.512502]? __ps2_command+0x372/0x7e0 [6.512516] __kasan_report.cold+0x7d/0x112 [6.512527] ? _raw_write_lock_irq+0x20/0xd0 [6.512539]? __ps2_command+0x372/0x7e0 [ 6.512552] kasan_report+0x3c/0x50 [ 6.512564] __asan_load1+0x6a/0x70 [ 6.512575] __ps2_command+0x372/0x7e0 [ 6.512589] ? ps2_drain+0x240/0x240 [6.512601]? dev_printk_emit+0xa2/0xd3 [6.512612]? dev_vprintk_emit+0xc5/0xc5 [6.512621]? __kasan_check_write+0x14/0x20 [6.512634]? mutex_lock+0x8f/0xe0 [6.512643]? __mutex_lock_slowpath+0x20/0x20 [ 6.512655] ps2_command+0x52/0x90 [ 6.512670] elantech_ps2_command+0x4f/0xc0 [psmouse] [ 6.512734] elantech_change_report_id+0x1e6/0x256 [psmouse] [ 6.512799] ? elantech_report_trackpoint.constprop.0.cold+0xd/0xd [psmouse] [6.512863]? ps2_command+0x7f/0x90 [6.512877] elantech_query_info.cold+0x6bd/0x9ed [psmouse] [6.512943] ? elantech_setup_ps2+0x460/0x460 [psmouse] [6.513005]? psmouse_reset+0x69/0xb0 [psmouse] [6.513064]? psmouse_attr_set_helper+0x2a0/0x2a0 [psmouse] [6.513122]? phys_pmd_init+0x30e/0x521 [6.513137] elantech_init+0x8a/0x200 [psmouse] [6.513200]? elantech_init_ps2+0xf0/0xf0 [psmouse] [6.513249]? elantech_query_info+0x440/0x440 [psmouse] [6.513296]? synaptics_send_cmd+0x60/0x60 [psmouse] [6.513342]? elantech_query_info+0x440/0x440 [psmouse] [6.513388]? psmouse_try_protocol+0x11e/0x170 [psmouse] [6.513432] psmouse_extensions+0x65d/0x6e0 [psmouse] [6.513476]? psmouse_try_protocol+0x170/0x170 [psmouse] [6.513519]? mutex_unlock+0x22/0x40 [6.513526]? ps2_command+0x7f/0x90 [6.513536]? psmouse_probe+0xa3/0xf0 [psmouse] [ 6.513580] psmouse_switch_protocol+0x27d/0x2e0 [psmouse] [ 6.513624] psmouse_connect+0x272/0x530 [psmouse] [ 6.513669] serio_driver_probe+0x55/0x70 [ 6.513679] realmente_probe+0x190/0x720 [ 6.513689] driver_probe_device +0x160/0x1f0 [6.513697] dispositivo_driver_attach+0x119/0x130 [6.513705] ? dispositivo_driver_attach+0x130/0x130 [6.513713] __driver_attach+0xe7/0x1a0 [6.513720]? device_driver_attach+0x130/0x130 [6.513728] bus_for_each_dev+0xfb/0x150 [6.513738]? subsys_dev_iter_exit+0x10/0x10 [6.513748]? _raw_write_unlock_bh+0x30/0x30 [ 6.513757] driver_attach+0x2d/0x40 [ 6.513764] serio_handle_event+0x199/0x3d0 [ 6.513775] Process_one_work+0x471/0x740 [ 6.513785] trabajador_thread+0x2d2 /0x790 [6.513794] ? Process_one_work+0x740/0x740 [6.513802] kthread+0x1b4/0x1e0 [6.513809]? set_kthread_struct+0x80/0x80 [6.513816] ret_from_fork+0x22/0x30 [6.513832] La dirección del error pertenece a la página: [6.513838] página:00000000bc35e189 refcount:0 mapcount:0 mapeo:0000000000000000 index:0x0 pfn:0x1024d7 [6.513847] banderas: 0x17ffffc0000000(nodo=0|zona=2|lastcpupid=0x1fffff) [6.513860] sin procesar: 0