Cloudanix VulnDB

CVE-2021-47027

None

CVSS

—

EPSS

0.2%

Published

Feb 28, 2024

CISA due date

—

Cloudanix analysis

Schedule a fix SSVC: Track

Certain wireless network cards can cause a computer to crash during startup if a required support file is missing or damaged.

Exploitation
Local Privilege
Attacker needs
Local User
Complexity
High
Impact
Denial Of Service
Component
OS kernel
Class
Other
Remediation
Upgrade
Effort
Medium
Patch risk
Low

What it actually does

Missing firmware or download failure in the mt7921 PCI driver triggers an unhandled error path that calls pci_disable_msi and free_msi_irqs on a partially initialized device, hitting a BUG() in the MSI subsystem and causing a kernel panic.

Why it matters to the business

Workstations or servers using MediaTek mt7921 Wi-Fi hardware may experience sudden boot or driver-load failures and kernel panics when the firmware file is absent or corrupted, resulting in unplanned downtime and loss of wireless connectivity.

How an attack unfolds

An attacker with local access or the ability to tamper with the firmware filesystem can delete or corrupt the mt7921 firmware image; on next load the probe routine fails to handle the error, leading to the MSI cleanup crash and denial of service.

How to fix it

Apply the upstream fix that adds proper error handling around firmware download failure in mt7921_pci_probe; rebuild and deploy the patched kernel; ensure firmware files are present and intact before loading the driver.

How to confirm the fix worked

Confirm the patched kernel no longer panics when the firmware is deliberately removed; inspect dmesg for successful probe or graceful error messages instead of BUG at drivers/pci/msi.c; verify module load succeeds with correct firmware.

Typical attack path

  1. Gain local filesystem access or supply a malicious initramfs/image
  2. Remove or corrupt the mt7921 firmware blob
  3. Trigger driver probe via boot, modprobe, or PCI device attach
  4. Kernel hits BUG in free_msi_irqs and panics

How to detect it

Review kernel logs for the exact BUG at drivers/pci/msi.c:375 and the mt7921e probe stack trace; look for repeated pci_disable_msi calls followed by kernel panic during early boot or module insertion.

What your security team should do

  • Prioritize kernel updates on systems containing mt7921 hardware
  • Add firmware integrity checks to boot and update processes
  • Monitor for mt7921 probe failures in system logs

The record

In the Linux kernel, the following vulnerability has been resolved: mt76: mt7921: fix kernel crash when the firmware fails to download Fix kernel crash when the firmware is missing or fails to download. [ 9.444758] kernel BUG at drivers/pci/msi.c:375! [ 9.449363] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP [ 9.501033] pstate: a0400009 (NzCv daif +PAN -UAO) [ 9.505814] pc : free_msi_irqs+0x180/0x184 [ 9.509897] lr : free_msi_irqs+0x40/0x184 [ 9.513893] sp : ffffffc015193870 [ 9.517194] x29: ffffffc015193870 x28: 00000000f0e94fa2 [ 9.522492] x27: 0000000000000acd x26: 000000000000009a [ 9.527790] x25: ffffffc0152cee58 x24: ffffffdbb383e0d8 [ 9.533087] x23: ffffffdbb38628d0 x22: 0000000000040200 [ 9.538384] x21: ffffff8cf7de7318 x20: ffffff8cd65a2480 [ 9.543681] x19: ffffff8cf7de7000 x18: 0000000000000000 [ 9.548979] x17: ffffff8cf9ca03b4 x16: ffffffdc13ad9a34 [ 9.554277] x15: 0000000000000000 x14: 0000000000080800 [ 9.559575] x13: ffffff8cd65a2980 x12: 0000000000000000 [ 9.564873] x11: ffffff8cfa45d820 x10: ffffff8cfa45d6d0 [ 9.570171] x9 : 0000000000000040 x8 : ffffff8ccef1b780 [ 9.575469] x7 : aaaaaaaaaaaaaaaa x6 : 0000000000000000 [ 9.580766] x5 : ffffffdc13824900 x4 : ffffff8ccefe0000 [ 9.586063] x3 : 0000000000000000 x2 : 0000000000000000 [ 9.591362] x1 : 0000000000000125 x0 : ffffff8ccefe0000 [ 9.596660] Call trace: [ 9.599095] free_msi_irqs+0x180/0x184 [ 9.602831] pci_disable_msi+0x100/0x130 [ 9.606740] pci_free_irq_vectors+0x24/0x30 [ 9.610915] mt7921_pci_probe+0xbc/0x250 [mt7921e] [ 9.615693] pci_device_probe+0xd4/0x14c [ 9.619604] really_probe+0x134/0x2ec [ 9.623252] driver_probe_device+0x64/0xfc [ 9.627335] device_driver_attach+0x4c/0x6c [ 9.631506] __driver_attach+0xac/0xc0 [ 9.635243] bus_for_each_dev+0x8c/0xd4 [ 9.639066] driver_attach+0x2c/0x38 [ 9.642628] bus_add_driver+0xfc/0x1d0 [ 9.646365] driver_register+0x64/0xf8 [ 9.650101] __pci_register_driver+0x6c/0x7c [ 9.654360] init_module+0x28/0xfdc [mt7921e] [ 9.658704] do_one_initcall+0x13c/0x2d0 [ 9.662615] do_init_module+0x58/0x1e8 [ 9.666351] load_module+0xd80/0xeb4 [ 9.669912] __arm64_sys_finit_module+0xa8/0xe0 [ 9.674430] el0_svc_common+0xa4/0x16c [ 9.678168] el0_svc_compat_handler+0x2c/0x40 [ 9.682511] el0_svc_compat+0x8/0x10 [ 9.686076] Code: a94257f6 f9400bf7 a8c47bfd d65f03c0 (d4210000) [ 9.692155] ---[ end trace 7621f966afbf0a29 ]--- [ 9.697385] Kernel panic - not syncing: Fatal exception [ 9.702599] SMP: stopping secondary CPUs [ 9.706549] Kernel Offset: 0x1c03600000 from 0xffffffc010000000 [ 9.712456] PHYS_OFFSET: 0xfffffff440000000 [ 9.716625] CPU features: 0x080026,2a80aa18 [ 9.720795] Memory Limit: none

Affected packages

Ecosystem Package Introduced Fixed
Ubuntu:16.04:LTS linux-hwe-edge 0 No fix
Ubuntu:18.04:LTS linux-aws-5.0 0 No fix
Ubuntu:18.04:LTS linux-aws-5.3 0 No fix
Ubuntu:18.04:LTS linux-azure 0 No fix
Ubuntu:18.04:LTS linux-azure-5.3 0 No fix
Ubuntu:18.04:LTS linux-azure-edge 0 No fix
Ubuntu:18.04:LTS linux-gcp 0 No fix
Ubuntu:18.04:LTS linux-gcp-5.3 0 No fix
Ubuntu:18.04:LTS linux-gke-4.15 0 No fix
Ubuntu:18.04:LTS linux-gke-5.4 0 No fix
Ubuntu:18.04:LTS linux-gkeop-5.4 0 No fix
Ubuntu:18.04:LTS linux-hwe 0 No fix
Ubuntu:18.04:LTS linux-hwe-edge 0 No fix
Ubuntu:18.04:LTS linux-oem 0 No fix
Ubuntu:18.04:LTS linux-oracle-5.0 0 No fix
Ubuntu:18.04:LTS linux-oracle-5.3 0 No fix
Ubuntu:20.04:LTS linux 0 5.4.0-9.12
Ubuntu:20.04:LTS linux-aws 0 5.4.0-1005.5
Ubuntu:20.04:LTS linux-aws-5.11 0 No fix
Ubuntu:20.04:LTS linux-aws-5.13 0 No fix
Ubuntu:20.04:LTS linux-aws-5.15 0 5.15.0-1014.18~20.04.1
Ubuntu:20.04:LTS linux-aws-5.8 0 No fix
Ubuntu:20.04:LTS linux-azure 0 5.4.0-1006.6
Ubuntu:20.04:LTS linux-azure-5.11 0 No fix
Ubuntu:20.04:LTS linux-azure-5.13 0 No fix
Ubuntu:20.04:LTS linux-azure-5.15 0 5.15.0-1007.8~20.04.1
Ubuntu:20.04:LTS linux-azure-5.8 0 No fix
Ubuntu:20.04:LTS linux-azure-fde 0 No fix
Ubuntu:20.04:LTS linux-azure-fde-5.15 0 5.15.0-1019.24~20.04.1.1
Ubuntu:20.04:LTS linux-bluefield 0 5.4.0-1007.10
Ubuntu:20.04:LTS linux-gcp 0 5.4.0-1005.5
Ubuntu:20.04:LTS linux-gcp-5.11 0 No fix
Ubuntu:20.04:LTS linux-gcp-5.13 0 No fix
Ubuntu:20.04:LTS linux-gcp-5.15 0 5.15.0-1006.9~20.04.1
Ubuntu:20.04:LTS linux-gcp-5.8 0 No fix
Ubuntu:20.04:LTS linux-gke 0 No fix
Ubuntu:20.04:LTS linux-gke-5.15 0 No fix
Ubuntu:20.04:LTS linux-gkeop 0 5.4.0-1008.9
Ubuntu:20.04:LTS linux-gkeop-5.15 0 5.15.0-1003.5~20.04.2
Ubuntu:20.04:LTS linux-hwe-5.11 0 No fix
Ubuntu:20.04:LTS linux-hwe-5.13 0 No fix
Ubuntu:20.04:LTS linux-hwe-5.15 0 5.15.0-33.34~20.04.1
Ubuntu:20.04:LTS linux-hwe-5.8 0 No fix
Ubuntu:20.04:LTS linux-ibm 0 5.4.0-1003.4
Ubuntu:20.04:LTS linux-ibm-5.15 0 5.15.0-1033.36~20.04.1
Ubuntu:20.04:LTS linux-intel-5.13 0 No fix
Ubuntu:20.04:LTS linux-intel-iotg-5.15 0 5.15.0-1003.5~20.04.1
Ubuntu:20.04:LTS linux-iot 0 5.4.0-1001.3
Ubuntu:20.04:LTS linux-kvm 0 5.4.0-1004.4
Ubuntu:20.04:LTS linux-lowlatency-hwe-5.15 0 5.15.0-33.34~20.04.1
Ubuntu:20.04:LTS linux-oem-5.10 0 No fix
Ubuntu:20.04:LTS linux-oem-5.13 0 No fix
Ubuntu:20.04:LTS linux-oem-5.14 0 No fix
Ubuntu:20.04:LTS linux-oem-5.6 0 No fix
Ubuntu:20.04:LTS linux-oracle 0 5.4.0-1005.5
Ubuntu:20.04:LTS linux-oracle-5.11 0 No fix
Ubuntu:20.04:LTS linux-oracle-5.13 0 No fix
Ubuntu:20.04:LTS linux-oracle-5.15 0 5.15.0-1007.9~20.04.1
Ubuntu:20.04:LTS linux-oracle-5.8 0 No fix
Ubuntu:20.04:LTS linux-raspi 0 5.4.0-1007.7
Ubuntu:20.04:LTS linux-raspi2 0 No fix
Ubuntu:20.04:LTS linux-riscv 0 No fix
Ubuntu:20.04:LTS linux-riscv-5.11 0 No fix
Ubuntu:20.04:LTS linux-riscv-5.15 0 5.15.0-1015.17~20.04.1
Ubuntu:20.04:LTS linux-riscv-5.8 0 No fix
Ubuntu:20.04:LTS linux-xilinx-zynqmp 0 5.4.0-1020.24
Ubuntu:22.04:LTS linux 0 5.13.0-19.19
Ubuntu:22.04:LTS linux-allwinner-5.19 0 No fix
Ubuntu:22.04:LTS linux-aws 0 5.13.0-1005.6
Ubuntu:22.04:LTS linux-aws-5.19 0 No fix
Ubuntu:22.04:LTS linux-aws-6.2 0 No fix
Ubuntu:22.04:LTS linux-aws-6.5 0 6.5.0-1008.8~22.04.1
Ubuntu:22.04:LTS linux-azure 0 5.13.0-1006.7
Ubuntu:22.04:LTS linux-azure-5.19 0 No fix
Ubuntu:22.04:LTS linux-azure-6.2 0 No fix
Ubuntu:22.04:LTS linux-azure-6.5 0 6.5.0-1007.7~22.04.1
Ubuntu:22.04:LTS linux-azure-fde 0 5.15.0-1019.24.1
Ubuntu:22.04:LTS linux-azure-fde-5.19 0 No fix
Ubuntu:22.04:LTS linux-azure-fde-6.2 0 No fix
Ubuntu:22.04:LTS linux-gcp 0 5.13.0-1005.6
Ubuntu:22.04:LTS linux-gcp-5.19 0 No fix
Ubuntu:22.04:LTS linux-gcp-6.2 0 No fix
Ubuntu:22.04:LTS linux-gcp-6.5 0 6.5.0-1010.10~22.04.3
Ubuntu:22.04:LTS linux-gke 0 5.15.0-1002.2
Ubuntu:22.04:LTS linux-gkeop 0 5.15.0-1001.2
Ubuntu:22.04:LTS linux-hwe-5.19 0 No fix
Ubuntu:22.04:LTS linux-hwe-6.2 0 No fix
Ubuntu:22.04:LTS linux-hwe-6.5 0 6.5.0-14.14~22.04.1
Ubuntu:22.04:LTS linux-ibm 0 5.15.0-1002.2
Ubuntu:22.04:LTS linux-intel-iotg 0 5.15.0-1004.6
Ubuntu:22.04:LTS linux-kvm 0 5.13.0-1004.4
Ubuntu:22.04:LTS linux-lowlatency 0 5.15.0-22.22
Ubuntu:22.04:LTS linux-lowlatency-hwe-5.19 0 No fix
Ubuntu:22.04:LTS linux-lowlatency-hwe-6.2 0 No fix
Ubuntu:22.04:LTS linux-lowlatency-hwe-6.5 0 6.5.0-14.14.1~22.04.1
Ubuntu:22.04:LTS linux-nvidia 0 5.15.0-1005.5
Ubuntu:22.04:LTS linux-nvidia-6.2 0 No fix
Ubuntu:22.04:LTS linux-nvidia-6.5 0 6.5.0-1004.4
Ubuntu:22.04:LTS linux-nvidia-6.8 0 6.8.0-1008.8~22.04.1
Ubuntu:22.04:LTS linux-oem-5.17 0 No fix
Ubuntu:22.04:LTS linux-oem-6.0 0 No fix
Ubuntu:22.04:LTS linux-oem-6.1 0 No fix
Ubuntu:22.04:LTS linux-oem-6.5 0 6.5.0-1003.3
Ubuntu:22.04:LTS linux-oracle 0 5.13.0-1008.10
Ubuntu:22.04:LTS linux-oracle-6.5 0 6.5.0-1013.13~22.04.4
Ubuntu:22.04:LTS linux-raspi 0 5.13.0-1008.9
Ubuntu:22.04:LTS linux-riscv 0 No fix
Ubuntu:22.04:LTS linux-riscv-5.19 0 No fix
Ubuntu:22.04:LTS linux-riscv-6.5 0 6.5.0-17.17.1.1~22.04.1
Ubuntu:22.04:LTS linux-starfive-5.19 0 No fix
Ubuntu:22.04:LTS linux-starfive-6.2 0 No fix
Ubuntu:22.04:LTS linux-starfive-6.5 0 6.5.0-1007.8~22.04.1
Ubuntu:22.04:LTS linux-xilinx-zynqmp 0 5.15.0-1022.26
Ubuntu:24.04:LTS linux 0 6.5.0-9.9
Ubuntu:24.04:LTS linux-aws 0 6.5.0-1008.8
Ubuntu:24.04:LTS linux-azure 0 6.5.0-1007.7
Ubuntu:24.04:LTS linux-gcp 0 6.5.0-1007.7
Ubuntu:24.04:LTS linux-gke 0 6.8.0-1003.5
Ubuntu:24.04:LTS linux-gkeop 0 6.8.0-1001.3
Ubuntu:24.04:LTS linux-ibm 0 6.5.0-1009.9
Ubuntu:24.04:LTS linux-lowlatency 0 6.5.0-9.9.1
Ubuntu:24.04:LTS linux-nvidia 0 6.8.0-1007.7
Ubuntu:24.04:LTS linux-nvidia-lowlatency 0 6.8.0-1009.9.1
Ubuntu:24.04:LTS linux-oem-6.8 0 6.8.0-1003.3
Ubuntu:24.04:LTS linux-oracle 0 6.5.0-1010.10
Ubuntu:24.04:LTS linux-raspi 0 6.5.0-1005.7
Ubuntu:24.04:LTS linux-riscv 0 6.5.0-9.9.1
Ubuntu:Pro:16.04:LTS linux-hwe-edge 0 No fix
Ubuntu:Pro:18.04:LTS linux-aws-5.0 0 No fix
Ubuntu:Pro:18.04:LTS linux-aws-5.3 0 No fix
Ubuntu:Pro:18.04:LTS linux-azure 0 No fix
Ubuntu:Pro:18.04:LTS linux-azure-5.3 0 No fix
Ubuntu:Pro:18.04:LTS linux-azure-edge 0 No fix
Ubuntu:Pro:18.04:LTS linux-gcp 0 No fix
Ubuntu:Pro:18.04:LTS linux-gcp-5.3 0 No fix
Ubuntu:Pro:18.04:LTS linux-gke-4.15 0 No fix
Ubuntu:Pro:18.04:LTS linux-gke-5.4 0 No fix
Ubuntu:Pro:18.04:LTS linux-gkeop-5.4 0 No fix
Ubuntu:Pro:18.04:LTS linux-hwe 0 No fix
Ubuntu:Pro:18.04:LTS linux-hwe-edge 0 No fix
Ubuntu:Pro:18.04:LTS linux-oem 0 No fix
Ubuntu:Pro:18.04:LTS linux-oracle-5.0 0 No fix
Ubuntu:Pro:18.04:LTS linux-oracle-5.3 0 No fix
Ubuntu:Pro:20.04:LTS linux-aws-5.11 0 No fix
Ubuntu:Pro:20.04:LTS linux-aws-5.13 0 No fix
Ubuntu:Pro:20.04:LTS linux-aws-5.8 0 No fix
Ubuntu:Pro:20.04:LTS linux-azure-5.11 0 No fix
Ubuntu:Pro:20.04:LTS linux-azure-5.13 0 No fix
Ubuntu:Pro:20.04:LTS linux-azure-5.8 0 No fix
Ubuntu:Pro:20.04:LTS linux-azure-fde 0 No fix
Ubuntu:Pro:20.04:LTS linux-gcp-5.11 0 No fix
Ubuntu:Pro:20.04:LTS linux-gcp-5.13 0 No fix
Ubuntu:Pro:20.04:LTS linux-gcp-5.8 0 No fix
Ubuntu:Pro:20.04:LTS linux-gke 0 No fix
Ubuntu:Pro:20.04:LTS linux-gke-5.15 0 No fix
Ubuntu:Pro:20.04:LTS linux-hwe-5.11 0 No fix
Ubuntu:Pro:20.04:LTS linux-hwe-5.13 0 No fix
Ubuntu:Pro:20.04:LTS linux-hwe-5.8 0 No fix
Ubuntu:Pro:20.04:LTS linux-intel-5.13 0 No fix
Ubuntu:Pro:20.04:LTS linux-oem-5.10 0 No fix
Ubuntu:Pro:20.04:LTS linux-oem-5.13 0 No fix
Ubuntu:Pro:20.04:LTS linux-oem-5.14 0 No fix
Ubuntu:Pro:20.04:LTS linux-oem-5.6 0 No fix
Ubuntu:Pro:20.04:LTS linux-oracle-5.11 0 No fix
Ubuntu:Pro:20.04:LTS linux-oracle-5.13 0 No fix
Ubuntu:Pro:20.04:LTS linux-oracle-5.8 0 No fix
Ubuntu:Pro:20.04:LTS linux-raspi2 0 No fix
Ubuntu:Pro:20.04:LTS linux-riscv 0 No fix
Ubuntu:Pro:20.04:LTS linux-riscv-5.11 0 No fix
Ubuntu:Pro:20.04:LTS linux-riscv-5.8 0 No fix
Ubuntu:Pro:FIPS-updates:18.04:LTS linux-aws-fips 0 4.15.0-2000.4
Ubuntu:Pro:FIPS-updates:18.04:LTS linux-azure-fips 0 4.15.0-1002.2
Ubuntu:Pro:FIPS-updates:18.04:LTS linux-fips 0 4.15.0-1027.32
Ubuntu:Pro:FIPS-updates:18.04:LTS linux-gcp-fips 0 4.15.0-2013.14
Ubuntu:Pro:FIPS-updates:20.04:LTS linux-aws-fips 0 5.4.0-1021.21+fips2
Ubuntu:Pro:FIPS-updates:20.04:LTS linux-azure-fips 0 5.4.0-1022.22+fips1
Ubuntu:Pro:FIPS-updates:20.04:LTS linux-fips 0 5.4.0-1026.30
Ubuntu:Pro:FIPS-updates:20.04:LTS linux-gcp-fips 0 5.4.0-1021.21+fips1
Ubuntu:Pro:FIPS:16.04:LTS linux-fips 0 4.4.0-1003.3
Ubuntu:Pro:FIPS:18.04:LTS linux-aws-fips 0 4.15.0-2000.4
Ubuntu:Pro:FIPS:18.04:LTS linux-azure-fips 0 4.15.0-1002.2
Ubuntu:Pro:FIPS:18.04:LTS linux-fips 0 4.15.0-1011.12
Ubuntu:Pro:FIPS:18.04:LTS linux-gcp-fips 0 4.15.0-1001.1
Ubuntu:Pro:FIPS:20.04:LTS linux-aws-fips 0 5.4.0-1021.21+fips2
Ubuntu:Pro:FIPS:20.04:LTS linux-azure-fips 0 5.4.0-1022.22+fips1
Ubuntu:Pro:FIPS:20.04:LTS linux-fips 0 5.4.0-1007.8
Ubuntu:Pro:FIPS:20.04:LTS linux-gcp-fips 0 5.4.0-1021.21+fips1

Related vulnerabilities