CVE-2024-26644

btrfs: don't abort filesystem when attempting to snapshot deleted subvolume

Severity Score

"-"

*CVSS v-

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

Track

*SSVC

Descriptions

In the Linux kernel, the following vulnerability has been resolved:

btrfs: don't abort filesystem when attempting to snapshot deleted subvolume

If the source file descriptor to the snapshot ioctl refers to a deleted
subvolume, we get the following abort:

BTRFS: Transaction aborted (error -2)
WARNING: CPU: 0 PID: 833 at fs/btrfs/transaction.c:1875 create_pending_snapshot+0x1040/0x1190 [btrfs]
Modules linked in: pata_acpi btrfs ata_piix libata scsi_mod virtio_net blake2b_generic xor net_failover virtio_rng failover scsi_common rng_core raid6_pq libcrc32c
CPU: 0 PID: 833 Comm: t_snapshot_dele Not tainted 6.7.0-rc6 #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-1.fc39 04/01/2014
RIP: 0010:create_pending_snapshot+0x1040/0x1190 [btrfs]
RSP: 0018:ffffa09c01337af8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff9982053e7c78 RCX: 0000000000000027
RDX: ffff99827dc20848 RSI: 0000000000000001 RDI: ffff99827dc20840
RBP: ffffa09c01337c00 R08: 0000000000000000 R09: ffffa09c01337998
R10: 0000000000000003 R11: ffffffffb96da248 R12: fffffffffffffffe
R13: ffff99820535bb28 R14: ffff99820b7bd000 R15: ffff99820381ea80
FS: 00007fe20aadabc0(0000) GS:ffff99827dc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000559a120b502f CR3: 00000000055b6000 CR4: 00000000000006f0
Call Trace:
<TASK>
? create_pending_snapshot+0x1040/0x1190 [btrfs]
? __warn+0x81/0x130
? create_pending_snapshot+0x1040/0x1190 [btrfs]
? report_bug+0x171/0x1a0
? handle_bug+0x3a/0x70
? exc_invalid_op+0x17/0x70
? asm_exc_invalid_op+0x1a/0x20
? create_pending_snapshot+0x1040/0x1190 [btrfs]
? create_pending_snapshot+0x1040/0x1190 [btrfs]
create_pending_snapshots+0x92/0xc0 [btrfs]
btrfs_commit_transaction+0x66b/0xf40 [btrfs]
btrfs_mksubvol+0x301/0x4d0 [btrfs]
btrfs_mksnapshot+0x80/0xb0 [btrfs]
__btrfs_ioctl_snap_create+0x1c2/0x1d0 [btrfs]
btrfs_ioctl_snap_create_v2+0xc4/0x150 [btrfs]
btrfs_ioctl+0x8a6/0x2650 [btrfs]
? kmem_cache_free+0x22/0x340
? do_sys_openat2+0x97/0xe0
__x64_sys_ioctl+0x97/0xd0
do_syscall_64+0x46/0xf0
entry_SYSCALL_64_after_hwframe+0x6e/0x76
RIP: 0033:0x7fe20abe83af
RSP: 002b:00007ffe6eff1360 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007fe20abe83af
RDX: 00007ffe6eff23c0 RSI: 0000000050009417 RDI: 0000000000000003
RBP: 0000000000000003 R08: 0000000000000000 R09: 00007fe20ad16cd0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe6eff13c0 R14: 00007fe20ad45000 R15: 0000559a120b6d58
</TASK>
---[ end trace 0000000000000000 ]---
BTRFS: error (device vdc: state A) in create_pending_snapshot:1875: errno=-2 No such entry
BTRFS info (device vdc: state EA): forced readonly
BTRFS warning (device vdc: state EA): Skipping commit of aborted transaction.
BTRFS: error (device vdc: state EA) in cleanup_transaction:2055: errno=-2 No such entry

This happens because create_pending_snapshot() initializes the new root
item as a copy of the source root item. This includes the refs field,
which is 0 for a deleted subvolume. The call to btrfs_insert_root()
therefore inserts a root with refs == 0. btrfs_get_new_fs_root() then
finds the root and returns -ENOENT if refs == 0, which causes
create_pending_snapshot() to abort.

Fix it by checking the source root's refs before attempting the
snapshot, but after locking subvol_sem to avoid racing with deletion.

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: btrfs: no aborte el sistema de archivos al intentar crear una instantánea del subvolumen eliminado. Si el descriptor del archivo fuente de la instantánea ioctl se refiere a un subvolumen eliminado, obtenemos la siguiente cancelación: BTRFS: transacción abortada (error -2) ADVERTENCIA: CPU: 0 PID: 833 en fs/btrfs/transaction.c:1875 create_pending_snapshot+0x1040/0x1190 [btrfs] Módulos vinculados en: pata_acpi btrfs ata_piix libata scsi_mod virtio_net blake2b_generic xor net_failover virtio_rng failover scsi_common rng_core raid6_pq libcrc32c CPU: 0 PID: 833 Comm: t_snapshot_dele No contaminado 6.7.0-rc6 #2 Nombre del hardware: PC estándar QEMU (i440FX + PIIX, 1996), BIOS 1.16.3-1.fc39 01/04/2014 RIP: 0010:create_pending_snapshot +0x1040/0x1190 [btrfs] RSP: 0018:ffffa09c01337af8 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffff9982053e7c78 RCX: 0000000000000027 RDX: ffff99 827dc20848 RSI: 0000000000000001 RDI: ffff99827dc20840 RBP: ffffa09c01337c00 R08: 00000000000000000 R09: ffffa09c01337998 R10: 000000000000000003 R11: ffffffffb96da248 R12: fffffffffffffffe R13: ffff99820535bb28 R14: ffff99820b7bd000 R15: ffff99820381ea80 FS: 00007fe20aadabc0(0000) GS:ffff99827dc00000(0000) knlGS:000000000000 0000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000559a120b502f CR3: 00000000055b6000 CR4: 00000000000006f0 Rastreo de llamadas: < TAREA> ? create_pending_snapshot+0x1040/0x1190 [btrfs]? __advertir+0x81/0x130 ? create_pending_snapshot+0x1040/0x1190 [btrfs]? report_bug+0x171/0x1a0? handle_bug+0x3a/0x70? exc_invalid_op+0x17/0x70? asm_exc_invalid_op+0x1a/0x20? create_pending_snapshot+0x1040/0x1190 [btrfs]? create_pending_snapshot+0x1040/0x1190 [btrfs] create_pending_snapshots+0x92/0xc0 [btrfs] btrfs_commit_transaction+0x66b/0xf40 [btrfs] btrfs_mksubvol+0x301/0x4d0 [btrfs] btrfs_mksnapshot+0x8 0/0xb0 [btrfs] __btrfs_ioctl_snap_create+0x1c2/0x1d0 [btrfs] btrfs_ioctl_snap_create_v2+ 0xc4/0x150 [btrfs] btrfs_ioctl+0x8a6/0x2650 [btrfs] ? kmem_cache_free+0x22/0x340? do_sys_openat2+0x97/0xe0 __x64_sys_ioctl+0x97/0xd0 do_syscall_64+0x46/0xf0 Entry_SYSCALL_64_after_hwframe+0x6e/0x76 RIP: 0033:0x7fe20abe83af RSP: 002b:00007ffe6eff13 60 EFLAGS: 00000246 ORIG_RAX: 00000000000000010 RAX: ffffffffffffffda RBX: 00000000000000004 RCX: 00007fe20abe83af RDX: 00007ffe6eff23c0 RSI: 0000000050009417 RDI: 0000000000000003 RBP: 0000000000000003 R08: 0000000000000000 R09: 00007fe20ad16cd0 R10: 0000000000000000 R11: 00 00000000000246 R12: 0000000000000000 R13: 00007ffe6eff13c0 R14: 00007fe20ad45000 R15: 0000559a120b6d58 ---[ final de seguimiento 0000000000000000 ]--- BTRFS: error ( dispositivo vdc: estado A) en create_pending_snapshot:1875: errno=-2 No existe tal entrada Información BTRFS (dispositivo vdc: estado EA): solo lectura forzada Advertencia BTRFS (dispositivo vdc: estado EA): omitir confirmación de transacción abortada. BTRFS: error (dispositivo vdc: estado EA) en cleanup_transaction:2055: errno=-2 No existe tal entrada. Esto sucede porque create_pending_snapshot() inicializa el nuevo elemento raíz como una copia del elemento raíz de origen. Esto incluye el campo de referencias, que es 0 para un subvolumen eliminado. Por lo tanto, la llamada a btrfs_insert_root() inserta una raíz con refs == 0. btrfs_get_new_fs_root() luego encuentra la raíz y devuelve -ENOENT si refs == 0, lo que hace que create_pending_snapshot() aborte. Solucionelo verificando las referencias de la raíz de origen antes de intentar la instantánea, pero después de bloquear subvol_sem para evitar correr con la eliminación.

*Credits: N/A

CVSS Scores

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Attack Complexity

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User Interaction

Scope

Confidentiality

Integrity

Availability

* Common Vulnerability Scoring System

SSVC

Decision:Track

Exploitation

None

Automatable

Tech. Impact

Partial

* Organization's Worst-case Scenario

Timeline

2024-02-19 CVE Reserved
2024-03-26 CVE Published
2024-03-27 EPSS Updated
2024-08-02 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CAPEC

References (7)

URL	Tag	Source
https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html

URL	Date	SRC

URL	Date	SRC
https://git.kernel.org/stable/c/2bdf872bcfe629a6202ffd6641615a8ed00e8464	2024-02-23
https://git.kernel.org/stable/c/0877497dc97834728e1b528ddf1e1c484292c29c	2024-02-23
https://git.kernel.org/stable/c/6e6bca99e8d88d989a7cde4c064abea552d5219b	2024-02-01
https://git.kernel.org/stable/c/ec794a7528199e1be6d47bec03f4755aa75df256	2024-02-01
https://git.kernel.org/stable/c/d8680b722f0ff6d7a01ddacc1844e0d52354d6ff	2024-02-01
https://git.kernel.org/stable/c/7081929ab2572920e94d70be3d332e5c9f97095a	2024-01-12

URL	Date	SRC

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 5.10.210 Search vendor "Linux" for product "Linux Kernel" and version " < 5.10.210"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 5.15.149 Search vendor "Linux" for product "Linux Kernel" and version " < 5.15.149"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 6.1.76 Search vendor "Linux" for product "Linux Kernel" and version " < 6.1.76"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 6.6.15 Search vendor "Linux" for product "Linux Kernel" and version " < 6.6.15"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 6.7.3 Search vendor "Linux" for product "Linux Kernel" and version " < 6.7.3"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 6.8 Search vendor "Linux" for product "Linux Kernel" and version " < 6.8"		en		Affected