CVE-2022-48847

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: watch_queue: corrige la verificación del límite del filtro En watch_queue_set_filter(), hay un par de lugares donde verificamos que el valor del tipo de filtro no exceda lo que puede contener el mapa de bits type_filter. Un lugar calcula el número de bits mediante: if (tf[i].type >= sizeof(wfilter->type_filter) * 8) lo cual está bien, pero el segundo sí: if (tf[i].type >= sizeof( wfilter->type_filter) * BITS_PER_LONG) que no lo es. Esto puede provocar un par de escrituras fuera de los límites debido a un tipo demasiado grande: (1) __set_bit() en wfilter->type_filter (2) Escribir más elementos en wfilter->filters[] de los que asignamos. Solucione este problema simplemente usando el WATCH_TYPE__NR adecuado, que es la cantidad de tipos que realmente conocemos. El error puede provocar un error parecido a: ERROR: KASAN: slab-out-of-bounds in watch_queue_set_filter+0x659/0x740 Escritura de tamaño 4 en la dirección ffff88800d2c66bc mediante la tarea watch_queue_oob/611... Seguimiento de llamadas: dump_stack_lvl+ 0x45/0x59 print_address_description.constprop.0+0x1f/0x150 ... kasan_report.cold+0x7f/0x11b ... watch_queue_set_filter+0x659/0x740 ... __x64_sys_ioctl+0x127/0x190 do_syscall_64+0x43/0x90 entrada_ SYSCALL_64_after_hwframe+0x44/0xae Asignado por tarea 611: kasan_save_stack+0x1e/0x40 __kasan_kmalloc+0x81/0xa0 watch_queue_set_filter+0x23a/0x740 __x64_sys_ioctl+0x127/0x190 do_syscall_64+0x43/0x90 Entry_SYSCALL_64_after_hwframe+0x 44/0xae La dirección con errores pertenece al objeto en ffff88800d2c66a0 que pertenece al caché kmalloc-32 de tamaño 32 La dirección con errores se encuentra a 28 bytes dentro de la región de 32 bytes [ffff88800d2c66a0, ffff88800d2c66c0)

In the Linux kernel, the following vulnerability has been resolved: watch_queue: Fix filter limit check In watch_queue_set_filter(), there are a couple of places where we check that the filter type value does not exceed what the type_filter bitmap can hold. One place calculates the number of bits by: if (tf[i].type >= sizeof(wfilter->type_filter) * 8) which is fine, but the second does: if (tf[i].type >= sizeof(wfilter->type_filter) * BITS_PER_LONG) which is not. This can lead to a couple of out-of-bounds writes due to a too-large type: (1) __set_bit() on wfilter->type_filter (2) Writing more elements in wfilter->filters[] than we allocated. Fix this by just using the proper WATCH_TYPE__NR instead, which is the number of types we actually know about. The bug may cause an oops looking something like: BUG: KASAN: slab-out-of-bounds in watch_queue_set_filter+0x659/0x740 Write of size 4 at addr ffff88800d2c66bc by task watch_queue_oob/611 ... Call Trace: <TASK> dump_stack_lvl+0x45/0x59 print_address_description.constprop.0+0x1f/0x150 ... kasan_report.cold+0x7f/0x11b ... watch_queue_set_filter+0x659/0x740 ... __x64_sys_ioctl+0x127/0x190 do_syscall_64+0x43/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae Allocated by task 611: kasan_save_stack+0x1e/0x40 __kasan_kmalloc+0x81/0xa0 watch_queue_set_filter+0x23a/0x740 __x64_sys_ioctl+0x127/0x190 do_syscall_64+0x43/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff88800d2c66a0 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 28 bytes inside of 32-byte region [ffff88800d2c66a0, ffff88800d2c66c0)