CVE-2021-47242

mptcp: fix soft lookup in subflow_error_report()

Severity Score

7.8

*CVSS v3.1

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:

mptcp: fix soft lookup in subflow_error_report()

Maxim reported a soft lookup in subflow_error_report():

watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:0]
RIP: 0010:native_queued_spin_lock_slowpath
RSP: 0018:ffffa859c0003bc0 EFLAGS: 00000202
RAX: 0000000000000101 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff9195c2772d88 RSI: 0000000000000000 RDI: ffff9195c2772d88
RBP: ffff9195c2772d00 R08: 00000000000067b0 R09: c6e31da9eb1e44f4
R10: ffff9195ef379700 R11: ffff9195edb50710 R12: ffff9195c2772d88
R13: ffff9195f500e3d0 R14: ffff9195ef379700 R15: ffff9195ef379700
FS: 0000000000000000(0000) GS:ffff91961f400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c000407000 CR3: 0000000002988000 CR4: 00000000000006f0
Call Trace:
<IRQ>
_raw_spin_lock_bh
subflow_error_report
mptcp_subflow_data_available
__mptcp_move_skbs_from_subflow
mptcp_data_ready
tcp_data_queue
tcp_rcv_established
tcp_v4_do_rcv
tcp_v4_rcv
ip_protocol_deliver_rcu
ip_local_deliver_finish
__netif_receive_skb_one_core
netif_receive_skb
rtl8139_poll 8139too
__napi_poll
net_rx_action
__do_softirq
__irq_exit_rcu
common_interrupt
</IRQ>

The calling function - mptcp_subflow_data_available() - can be invoked
from different contexts:
- plain ssk socket lock
- ssk socket lock + mptcp_data_lock
- ssk socket lock + mptcp_data_lock + msk socket lock.

Since subflow_error_report() tries to acquire the mptcp_data_lock, the
latter two call chains will cause soft lookup.

This change addresses the issue moving the error reporting call to
outer functions, where the held locks list is known and the we can
acquire only the needed one.

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: mptcp: corrige una búsqueda suave en subflow_error_report(). Maxim informó una búsqueda suave en subflow_error_report(): vigilancia: ERROR: bloqueo suave - ¡CPU#0 bloqueada durante 22 segundos! [swapper/0:0] RIP: 0010:native_queued_spin_lock_slowpath RSP: 0018:ffffa859c0003bc0 EFLAGS: 00000202 RAX: 0000000000000101 RBX: 0000000000000001 RCX: 000000000 0000000 RDX: ffff9195c2772d88 RSI: 0000000000000000 RDI: ffff9195c2772d88 RBP: ffff9195c2772d00 R08: 00000000000067b0 R09: c6e31da9eb1e44f4 :ffff9195ef379700 R11: ffff9195edb50710 R12: ffff9195c2772d88 R13: ffff9195f500e3d0 R14: ffff9195ef379700 R15: ffff9195ef379700 FS: 0000000000000000(0000) 1961f400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c000407000 CR3: 0000000002988000 00000000000006f0 Seguimiento de llamadas: _raw_spin_lock_bh subflow_error_report mptcp_subflow_data_available __mptcp_move_skbs_from_subflow mptcp_data_ready tcp_data_queue tcp_rcv_establecido tcp_v4_do_rcv tcp_v4_rcv liver_rcu ip_local_deliver_finish __netif_receive_skb_one_core netif_receive_skb rtl8139_poll 8139too __napi_poll net_rx_action __do_softirq __irq_exit_rcu common_interrupt La función de llamada, mptcp_subflow_data_available(), se puede invocar desde diferentes contextos: - enchufe ssk lock - bloqueo de socket ssk + mptcp_data_lock - bloqueo de socket ssk + mptcp_data_lock + bloqueo de socket msk. Dado que subflow_error_report() intenta adquirir mptcp_data_lock, las dos últimas cadenas de llamadas provocarán una búsqueda suave. Este cambio soluciona el problema de mover la llamada de informe de errores a funciones externas, donde se conoce la lista de bloqueos retenidos y solo podemos adquirir el que necesitamos.

*Credits: N/A

CVSS Scores

CISAv3.1 7.8

Attack Vector

Local

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

* Common Vulnerability Scoring System

SSVC

Decision:Track*

Exploitation

None

Automatable

Tech. Impact

Total

* Organization's Worst-case Scenario

Timeline

2024-04-10 CVE Reserved
2024-05-21 CVE Published
2024-05-22 EPSS Updated
2024-08-04 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-667: Improper Locking

CAPEC

References (4)

URL	Tag	Source
https://git.kernel.org/stable/c/15cc10453398c22f78f6c2b897119ecce5e5dd89	Vuln. Introduced
https://git.kernel.org/stable/c/c8ad65cb5051498b8a58be40499db9e930f0092e	Vuln. Introduced

URL	Date	SRC

URL	Date	SRC
https://git.kernel.org/stable/c/27ef25c72373222aaa5fe7b5cd890ae9cfb89a8d	2021-06-23
https://git.kernel.org/stable/c/499ada5073361c631f2a3c4a8aed44d53b6f82ec	2021-06-10

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"				>= 5.12 < 5.12.13 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.12 < 5.12.13"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.12 < 5.13 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.12 < 5.13"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				5.11.12 Search vendor "Linux" for product "Linux Kernel" and version "5.11.12"		en		Affected