CVE-2024-26944

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: btrfs:zoned: corrige use-after-free en do_zone_finish() Shinichiro informó el siguiente use-after-free desencadenado por la operación de reemplazo de dispositivo en fstests btrfs/070. Información BTRFS (dispositivo nullb1): limpieza: finalizado en el dispositivo 1 con estado: 0 ================================== ================================= ERROR: KASAN: uso de losa después de liberarlo en do_zone_finish+0x91a/0xb90 [btrfs] Lectura del tamaño 8 en la dirección ffff8881543c8060 mediante la tarea btrfs-cleaner/3494007 CPU: 0 PID: 3494007 Comm: btrfs-cleaner Contaminado: GW 6.8.0-rc5-kts #1 Nombre del hardware: Supermicro Super Server/X11SPi-TF , BIOS 3.3 21/02/2020 Seguimiento de llamadas: dump_stack_lvl+0x5b/0x90 print_report+0xcf/0x670 ? __virt_addr_valid+0x200/0x3e0 kasan_report+0xd8/0x110 ? do_zone_finish+0x91a/0xb90 [btrfs]? do_zone_finish+0x91a/0xb90 [btrfs] do_zone_finish+0x91a/0xb90 [btrfs] btrfs_delete_unused_bgs+0x5e1/0x1750 [btrfs] ? __pfx_btrfs_delete_unused_bgs+0x10/0x10 [btrfs] ? btrfs_put_root+0x2d/0x220 [btrfs] ? btrfs_clean_one_deleted_snapshot+0x299/0x430 [btrfs] clean_kthread+0x21e/0x380 [btrfs] ? __pfx_cleaner_kthread+0x10/0x10 [btrfs] kthread+0x2e3/0x3c0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x31/0x70 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1b/0x30 Asignado por tarea 3493983: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 btrfs_alloc_device+0x b3/0x4e0 [btrfs] lista_dispositivo_add.constprop.0+0x993/ 0x1630 [btrfs] btrfs_scan_one_device+0x219/0x3d0 [btrfs] btrfs_control_ioctl+0x26e/0x310 [btrfs] __x64_sys_ioctl+0x134/0x1b0 do_syscall_64+0x99/0x190 entrada_SYSCALL_6 4_after_hwframe+0x6e/0x76 Liberado por la tarea 3494056: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3f/0x60 veneno_slab_object+0x102/0x170 __kasan_slab_free+0x32/0x70 kfree+0x11b/0x320 btrfs_rm_dev_replace_free_srcdev+0xca/0x280 [btrfs_dev_replace_finishing+0xd 7e/0x14f0 [btrfs] btrfs_dev_replace_by_ioctl+0x1286/0x25a0 [btrfs] btrfs_ioctl+0xb27/0x57d0 [ btrfs] __x64_sys_ioctl+0x134/0x1b0 do_syscall_64+0x99/0x190 Entry_SYSCALL_64_after_hwframe+0x6e/0x76 La dirección con errores pertenece al objeto en ffff8881543c8000 que pertenece al caché kmalloc-1k de tamaño 1024 Se encuentra la dirección con errores 96 bytes dentro de los 1024 bytes liberados región [ffff8881543c8000, ffff8881543c8400) La dirección del error pertenece a la página física: página:00000000fe2c1285 refcount:1 mapcount:0 mapeo:00000000000000000 index:0x0 pfn:0x1543c8 head:00000000fe2c1285 entero_mapcount:0 nr_pages_mapped:0 pincount:0 banderas: 0x17ffffc0000840(slab|head|node=0|zone=2|lastcpupid=0x1fffff) tipo de página: 0xffffffff() raw: 0017ffffc0000840 ffff888100042dc0 ffffea0019e8f200 dead000000000002 raw: 0000000000 0000000000100010 00000001ffffffff 0000000000000000 página volcada porque: kasan: mal acceso detectado Estado de la memoria alrededor de la dirección con errores : ffff8881543c7f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8881543c7f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff8881543c8000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881543c8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881543c8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb Esta UAF sucede porque estamos acceder a información de zona obsoleta de un btrfs_device ya eliminado en do_zone_finish(). La secuencia de eventos es la siguiente: btrfs_dev_replace_start btrfs_scrub_dev btrfs_dev_replace_finishing btrfs_dev_replace_update_device_in_mapping_tree <-- dispositivos reemplazados btrfs_rm_dev_replace_free_srcdev btrfs_free_device <-- dispositivo liberado clean_kthread btrfs_delete_unused_ bgs btrfs_zone_finish do_zone_finish <-- hace referencia al dispositivo liberado. La razón de esto es que estamos usando un ---truncado ---

In the Linux kernel, the following vulnerability has been resolved: btrfs: zoned: fix use-after-free in do_zone_finish() Shinichiro reported the following use-after-free triggered by the device replace operation in fstests btrfs/070. BTRFS info (device nullb1): scrub: finished on devid 1 with status: 0 ================================================================== BUG: KASAN: slab-use-after-free in do_zone_finish+0x91a/0xb90 [btrfs] Read of size 8 at addr ffff8881543c8060 by task btrfs-cleaner/3494007 CPU: 0 PID: 3494007 Comm: btrfs-cleaner Tainted: G W 6.8.0-rc5-kts #1 Hardware name: Supermicro Super Server/X11SPi-TF, BIOS 3.3 02/21/2020 Call Trace: <TASK> dump_stack_lvl+0x5b/0x90 print_report+0xcf/0x670 ? __virt_addr_valid+0x200/0x3e0 kasan_report+0xd8/0x110 ? do_zone_finish+0x91a/0xb90 [btrfs] ? do_zone_finish+0x91a/0xb90 [btrfs] do_zone_finish+0x91a/0xb90 [btrfs] btrfs_delete_unused_bgs+0x5e1/0x1750 [btrfs] ? __pfx_btrfs_delete_unused_bgs+0x10/0x10 [btrfs] ? btrfs_put_root+0x2d/0x220 [btrfs] ? btrfs_clean_one_deleted_snapshot+0x299/0x430 [btrfs] cleaner_kthread+0x21e/0x380 [btrfs] ? __pfx_cleaner_kthread+0x10/0x10 [btrfs] kthread+0x2e3/0x3c0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x31/0x70 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1b/0x30 </TASK> Allocated by task 3493983: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 btrfs_alloc_device+0xb3/0x4e0 [btrfs] device_list_add.constprop.0+0x993/0x1630 [btrfs] btrfs_scan_one_device+0x219/0x3d0 [btrfs] btrfs_control_ioctl+0x26e/0x310 [btrfs] __x64_sys_ioctl+0x134/0x1b0 do_syscall_64+0x99/0x190 entry_SYSCALL_64_after_hwframe+0x6e/0x76 Freed by task 3494056: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3f/0x60 poison_slab_object+0x102/0x170 __kasan_slab_free+0x32/0x70 kfree+0x11b/0x320 btrfs_rm_dev_replace_free_srcdev+0xca/0x280 [btrfs] btrfs_dev_replace_finishing+0xd7e/0x14f0 [btrfs] btrfs_dev_replace_by_ioctl+0x1286/0x25a0 [btrfs] btrfs_ioctl+0xb27/0x57d0 [btrfs] __x64_sys_ioctl+0x134/0x1b0 do_syscall_64+0x99/0x190 entry_SYSCALL_64_after_hwframe+0x6e/0x76 The buggy address belongs to the object at ffff8881543c8000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 96 bytes inside of freed 1024-byte region [ffff8881543c8000, ffff8881543c8400) The buggy address belongs to the physical page: page:00000000fe2c1285 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1543c8 head:00000000fe2c1285 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x17ffffc0000840(slab|head|node=0|zone=2|lastcpupid=0x1fffff) page_type: 0xffffffff() raw: 0017ffffc0000840 ffff888100042dc0 ffffea0019e8f200 dead000000000002 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8881543c7f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8881543c7f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff8881543c8000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881543c8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881543c8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb This UAF happens because we're accessing stale zone information of a already removed btrfs_device in do_zone_finish(). The sequence of events is as follows: btrfs_dev_replace_start btrfs_scrub_dev btrfs_dev_replace_finishing btrfs_dev_replace_update_device_in_mapping_tree <-- devices replaced btrfs_rm_dev_replace_free_srcdev btrfs_free_device <-- device freed cleaner_kthread btrfs_delete_unused_bgs btrfs_zone_finish do_zone_finish <-- refers the freed device The reason for this is that we're using a ---truncated---