CVE-2021-47349
Description
From CVE.org
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]
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4.4 | 5.5 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | High | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Other); DoS: Crash, Exit, or Restart
Each thread of execution will "hang" and prevent tasks from completing. In some cases, CPU consumption may occur if a lock check occurs in a tight loop.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
