// For flags

CVE-2022-48862

vhost: fix hung thread due to erroneous iotlb entries

Severity Score

5.5
*CVSS v3.1

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:

vhost: fix hung thread due to erroneous iotlb entries

In vhost_iotlb_add_range_ctx(), range size can overflow to 0 when
start is 0 and last is ULONG_MAX. One instance where it can happen
is when userspace sends an IOTLB message with iova=size=uaddr=0
(vhost_process_iotlb_msg). So, an entry with size = 0, start = 0,
last = ULONG_MAX ends up in the iotlb. Next time a packet is sent,
iotlb_access_ok() loops indefinitely due to that erroneous entry.

Call Trace:
<TASK>
iotlb_access_ok+0x21b/0x3e0 drivers/vhost/vhost.c:1340
vq_meta_prefetch+0xbc/0x280 drivers/vhost/vhost.c:1366
vhost_transport_do_send_pkt+0xe0/0xfd0 drivers/vhost/vsock.c:104
vhost_worker+0x23d/0x3d0 drivers/vhost/vhost.c:372
kthread+0x2e9/0x3a0 kernel/kthread.c:377
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>

Reported by syzbot at:
https://syzkaller.appspot.com/bug?extid=0abd373e2e50d704db87

To fix this, do two things:

1. Return -EINVAL in vhost_chr_write_iter() when userspace asks to map
a range with size 0.
2. Fix vhost_iotlb_add_range_ctx() to handle the range [0, ULONG_MAX]
by splitting it into two entries.

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: vhost: corrige el hilo colgado debido a entradas erróneas de iotlb En vhost_iotlb_add_range_ctx(), el tamaño del rango puede desbordarse a 0 cuando el inicio es 0 y el último es ULONG_MAX. Un caso en el que puede suceder es cuando el espacio de usuario envía un mensaje IOTLB con iova=size=uaddr=0 (vhost_process_iotlb_msg). Entonces, una entrada con tamaño = 0, inicio = 0, último = ULONG_MAX termina en iotlb. La próxima vez que se envíe un paquete, iotlb_access_ok() se repite indefinidamente debido a esa entrada errónea. Seguimiento de llamadas: iotlb_access_ok+0x21b/0x3e0 drivers/vhost/vhost.c:1340 vq_meta_prefetch+0xbc/0x280 drivers/vhost/vhost.c:1366 vhost_transport_do_send_pkt+0xe0/0xfd0 drivers/vhost/vsock.c:104 vhost_worker+ 0x23d/0x3d0 drivers/vhost/vhost.c:372 kthread+0x2e9/0x3a0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Reportado por syzbot en: https ://syzkaller.appspot.com/bug?extid=0abd373e2e50d704db87 Para solucionar este problema, haga dos cosas: 1. Devuelva -EINVAL en vhost_chr_write_iter() cuando el espacio de usuario solicite asignar un rango con tamaño 0. 2. Corrija vhost_iotlb_add_range_ctx() para manejar el rango [0, ULONG_MAX] dividiéndolo en dos entradas.

*Credits: N/A
CVSS Scores
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
* Common Vulnerability Scoring System
SSVC
  • Decision:Track
Exploitation
None
Automatable
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2024-07-16 CVE Reserved
  • 2024-07-16 CVE Published
  • 2024-07-24 EPSS Updated
  • 2024-12-19 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')
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"
>= 5.7 < 5.15.29
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.7 < 5.15.29"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 5.7 < 5.16.15
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.7 < 5.16.15"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 5.7 < 5.17
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.7 < 5.17"
en
Affected