// For flags

CVE-2021-47599

btrfs: use latest_dev in btrfs_show_devname

Severity Score

"-"
*CVSS v-

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track
*SSVC
Descriptions

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

btrfs: use latest_dev in btrfs_show_devname

The test case btrfs/238 reports the warning below:

WARNING: CPU: 3 PID: 481 at fs/btrfs/super.c:2509 btrfs_show_devname+0x104/0x1e8 [btrfs]
CPU: 2 PID: 1 Comm: systemd Tainted: G W O 5.14.0-rc1-custom #72
Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
Call trace:
btrfs_show_devname+0x108/0x1b4 [btrfs]
show_mountinfo+0x234/0x2c4
m_show+0x28/0x34
seq_read_iter+0x12c/0x3c4
vfs_read+0x29c/0x2c8
ksys_read+0x80/0xec
__arm64_sys_read+0x28/0x34
invoke_syscall+0x50/0xf8
do_el0_svc+0x88/0x138
el0_svc+0x2c/0x8c
el0t_64_sync_handler+0x84/0xe4
el0t_64_sync+0x198/0x19c

Reason:
While btrfs_prepare_sprout() moves the fs_devices::devices into
fs_devices::seed_list, the btrfs_show_devname() searches for the devices
and found none, leading to the warning as in above.

Fix:
latest_dev is updated according to the changes to the device list.
That means we could use the latest_dev->name to show the device name in
/proc/self/mounts, the pointer will be always valid as it's assigned
before the device is deleted from the list in remove or replace.
The RCU protection is sufficient as the device structure is freed after
synchronization.

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: btrfs: utilice Latest_dev en btrfs_show_devname El caso de prueba btrfs/238 informa la siguiente advertencia: ADVERTENCIA: CPU: 3 PID: 481 en fs/btrfs/super.c:2509 btrfs_show_devname+0x104 /0x1e8 [btrfs] CPU: 2 PID: 1 Comunicación: systemd Contaminado: GWO 5.14.0-rc1-custom #72 Nombre de hardware: QEMU Máquina virtual QEMU, BIOS 0.0.0 06/02/2015 Rastreo de llamadas: btrfs_show_devname+0x108/ 0x1b4 [btrfs] show_mountinfo+0x234/0x2c4 m_show+0x28/0x34 seq_read_iter+0x12c/0x3c4 vfs_read+0x29c/0x2c8 ksys_read+0x80/0xec __arm64_sys_read+0x28/0x34 x50/0xf8 do_el0_svc+0x88/0x138 el0_svc+0x2c/0x8c el0t_64_sync_handler +0x84/0xe4 el0t_64_sync+0x198/0x19c Motivo: mientras btrfs_prepare_sprout() mueve fs_devices::devices a fs_devices::seed_list, btrfs_show_devname() busca los dispositivos y no encuentra ninguno, lo que genera la advertencia como se muestra arriba. Solución: last_dev se actualiza según los cambios en la lista de dispositivos. Eso significa que podríamos usar el último_dev->name para mostrar el nombre del dispositivo en /proc/self/mounts, el puntero siempre será válido tal como está asignado antes de que el dispositivo se elimine de la lista en eliminar o reemplazar. La protección de la RCU es suficiente, ya que la estructura del dispositivo se libera después de la sincronización.

*Credits: N/A
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* Common Vulnerability Scoring System
SSVC
  • Decision:Track
Exploitation
None
Automatable
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2024-05-24 CVE Reserved
  • 2024-06-19 CVE Published
  • 2024-06-20 EPSS Updated
  • 2024-09-11 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
CAPEC
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"
 < 5.15.11
Search vendor "Linux" for product "Linux Kernel" and version " < 5.15.11"
en
Affected
Linux
Search vendor "Linux"
 Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
 < 5.16
Search vendor "Linux" for product "Linux Kernel" and version " < 5.16"
en
Affected