CVE-2021-47349

mwifiex: bring down link before deleting interface

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:

mwifiex: bring down link before deleting interface

We can deadlock when rmmod'ing the driver or going through firmware
reset, because the cfg80211_unregister_wdev() has to bring down the link
for us, ... which then grab the same wiphy lock.

nl80211_del_interface() already handles a very similar case, with a nice
description:

/*
* We hold RTNL, so this is safe, without RTNL opencount cannot
* reach 0, and thus the rdev cannot be deleted.
*
* We need to do it for the dev_close(), since that will call
* the netdev notifiers, and we need to acquire the mutex there
* but don't know if we get there from here or from some other
* place (e.g. "ip link set ... down").
*/
mutex_unlock(&rdev->wiphy.mtx);
...

Do similarly for mwifiex teardown, by ensuring we bring the link down
first.

Sample deadlock trace:

[ 247.103516] INFO: task rmmod:2119 blocked for more than 123 seconds.
[ 247.110630] Not tainted 5.12.4 #5
[ 247.115796] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 247.124557] task:rmmod state:D stack: 0 pid: 2119 ppid: 2114 flags:0x00400208
[ 247.133905] Call trace:
[ 247.136644] __switch_to+0x130/0x170
[ 247.140643] __schedule+0x714/0xa0c
[ 247.144548] schedule_preempt_disabled+0x88/0xf4
[ 247.149714] __mutex_lock_common+0x43c/0x750
[ 247.154496] mutex_lock_nested+0x5c/0x68
[ 247.158884] cfg80211_netdev_notifier_call+0x280/0x4e0 [cfg80211]
[ 247.165769] raw_notifier_call_chain+0x4c/0x78
[ 247.170742] call_netdevice_notifiers_info+0x68/0xa4
[ 247.176305] __dev_close_many+0x7c/0x138
[ 247.180693] dev_close_many+0x7c/0x10c
[ 247.184893] unregister_netdevice_many+0xfc/0x654
[ 247.190158] unregister_netdevice_queue+0xb4/0xe0
[ 247.195424] _cfg80211_unregister_wdev+0xa4/0x204 [cfg80211]
[ 247.201816] cfg80211_unregister_wdev+0x20/0x2c [cfg80211]
[ 247.208016] mwifiex_del_virtual_intf+0xc8/0x188 [mwifiex]
[ 247.214174] mwifiex_uninit_sw+0x158/0x1b0 [mwifiex]
[ 247.219747] mwifiex_remove_card+0x38/0xa0 [mwifiex]
[ 247.225316] mwifiex_pcie_remove+0xd0/0xe0 [mwifiex_pcie]
[ 247.231451] pci_device_remove+0x50/0xe0
[ 247.235849] device_release_driver_internal+0x110/0x1b0
[ 247.241701] driver_detach+0x5c/0x9c
[ 247.245704] bus_remove_driver+0x84/0xb8
[ 247.250095] driver_unregister+0x3c/0x60
[ 247.254486] pci_unregister_driver+0x2c/0x90
[ 247.259267] cleanup_module+0x18/0xcdc [mwifiex_pcie]

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: mwifiex: desactivar el enlace antes de eliminar la interfaz. Podemos bloquearnos al modificar el controlador o restablecer el firmware, porque cfg80211_unregister_wdev() tiene que desactivar el enlace por nosotros. .. que luego agarra el mismo candado wiphy. nl80211_del_interface() ya maneja un caso muy similar, con una buena descripción: /* * Mantenemos RTNL, por lo que esto es seguro, sin RTNL opencount no puede * llegar a 0 y, por lo tanto, rdev no se puede eliminar. * * Necesitamos hacerlo para dev_close(), ya que eso llamará * a los notificadores de netdev, y necesitamos adquirir el mutex allí * pero no sabemos si llegamos allí desde aquí o desde algún otro * lugar (por ejemplo "enlace IP configurado... inactivo"). */ mutex_unlock(&rdev->wiphy.mtx); ... Haga lo mismo con el desmontaje de mwifiex, asegurándose de que primero desconectamos el enlace. Ejemplo de seguimiento de interbloqueo: [247.103516] INFORMACIÓN: tarea rmmod:2119 bloqueada durante más de 123 segundos. [247.110630] No contaminado 5.12.4 #5 [247.115796] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" desactiva este mensaje. [247.124557] tarea:rmmod estado:D pila: 0 pid: 2119 ppid: 2114 banderas:0x00400208 [247.133905] Rastreo de llamadas: [247.136644] __switch_to+0x130/0x170 [ 247.140643] 14/0xa0c [247.144548] Schedule_preempt_disabled+0x88/ 0xf4 [ 247.149714] __mutex_lock_common+0x43c/0x750 [ 247.154496] mutex_lock_nested+0x5c/0x68 [ 247.158884] cfg80211_netdev_notifier_call+0x280/0x4e0 [cfg80211] [ 47.165769] raw_notifier_call_chain+0x4c/0x78 [ 247.170742] call_netdevice_notifiers_info+0x68/0xa4 [ 247.176305] __dev_close_many+0x7c /0x138 [ 247.180693] dev_close_many+0x7c/0x10c [ 247.184893] unregister_netdevice_many+0xfc/0x654 [ 247.190158] unregister_netdevice_queue+0xb4/0xe0 [ 247.195424] 11_unregister_wdev+0xa4/0x204 [cfg80211] [ 247.201816] cfg80211_unregister_wdev+0x20/0x2c [cfg80211] [ 247.208016 ] mwifiex_del_virtual_intf+0xc8/0x188 [mwifiex] [ 247.214174] mwifiex_uninit_sw+0x158/0x1b0 [mwifiex] [ 247.219747] mwifiex_remove_card+0x38/0xa0 [mwifiex] [ 247.225316 ] mwifiex_pcie_remove+0xd0/0xe0 [mwifiex_pcie] [ 247.231451] pci_device_remove+0x50/0xe0 [ 247.235849] device_release_driver_internal+0x110/0x1b0 [ 247.241701] driver_detach+0x5c/0x9c [ 247.245704] bus_remove_driver+0x84/0xb8 [ 247.250095] driver_unregister+0x3c/0x60 [ 2 47.254486] pci_unregister_driver+0x2c/0x90 [ 247.259267] cleanup_module+0x18/0xcdc [mwifiex_pcie ]

*Credits: N/A

CVSS Scores

Attack Vector

Attack Complexity

Privileges Required

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

2024-05-21 CVE Reserved
2024-05-21 CVE Published
2024-05-22 EPSS Updated
2024-09-11 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CAPEC

References (4)

URL	Tag	Source
https://git.kernel.org/stable/c/a05829a7222e9d10c416dd2dbbf3929fe6646b89	Vuln. Introduced

URL	Date	SRC

URL	Date	SRC
https://git.kernel.org/stable/c/a3041d39d3c14da97fa3476835aba043ba810cf0	2021-07-19
https://git.kernel.org/stable/c/35af69c7c0490fdccfc159c6a87e4d1dc070838a	2021-07-19
https://git.kernel.org/stable/c/1f9482aa8d412b4ba06ce6ab8e333fb8ca29a06e	2021-06-11

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 < 5.12.18 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.12 < 5.12.18"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.12 < 5.13.3 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.12 < 5.13.3"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.12 < 5.14 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.12 < 5.14"		en		Affected