// For flags

CVE-2021-47390

KVM: x86: Fix stack-out-of-bounds memory access from ioapic_write_indirect()

Severity Score

"-"
*CVSS v-

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:

KVM: x86: Fix stack-out-of-bounds memory access from ioapic_write_indirect()

KASAN reports the following issue:

BUG: KASAN: stack-out-of-bounds in kvm_make_vcpus_request_mask+0x174/0x440 [kvm]
Read of size 8 at addr ffffc9001364f638 by task qemu-kvm/4798

CPU: 0 PID: 4798 Comm: qemu-kvm Tainted: G X --------- ---
Hardware name: AMD Corporation DAYTONA_X/DAYTONA_X, BIOS RYM0081C 07/13/2020
Call Trace:
dump_stack+0xa5/0xe6
print_address_description.constprop.0+0x18/0x130
? kvm_make_vcpus_request_mask+0x174/0x440 [kvm]
__kasan_report.cold+0x7f/0x114
? kvm_make_vcpus_request_mask+0x174/0x440 [kvm]
kasan_report+0x38/0x50
kasan_check_range+0xf5/0x1d0
kvm_make_vcpus_request_mask+0x174/0x440 [kvm]
kvm_make_scan_ioapic_request_mask+0x84/0xc0 [kvm]
? kvm_arch_exit+0x110/0x110 [kvm]
? sched_clock+0x5/0x10
ioapic_write_indirect+0x59f/0x9e0 [kvm]
? static_obj+0xc0/0xc0
? __lock_acquired+0x1d2/0x8c0
? kvm_ioapic_eoi_inject_work+0x120/0x120 [kvm]

The problem appears to be that 'vcpu_bitmap' is allocated as a single long
on stack and it should really be KVM_MAX_VCPUS long. We also seem to clear
the lower 16 bits of it with bitmap_zero() for no particular reason (my
guess would be that 'bitmap' and 'vcpu_bitmap' variables in
kvm_bitmap_or_dest_vcpus() caused the confusion: while the later is indeed
16-bit long, the later should accommodate all possible vCPUs).

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: KVM: x86: corrige el acceso a la memoria de pila fuera de los límites desde ioapic_write_indirect() KASAN informa el siguiente problema: BUG: KASAN: pila fuera de los límites en kvm_make_vcpus_request_mask+ 0x174/0x440 [kvm] Lectura de tamaño 8 en la dirección ffffc9001364f638 por tarea qemu-kvm/4798 CPU: 0 PID: 4798 Comm: qemu-kvm Contaminado: GX --------- --- Nombre de hardware: AMD Corporación DAYTONA_X/DAYTONA_X, BIOS RYM0081C 13/07/2020 Seguimiento de llamadas: dump_stack+0xa5/0xe6 print_address_description.constprop.0+0x18/0x130 ? kvm_make_vcpus_request_mask+0x174/0x440 [kvm] __kasan_report.cold+0x7f/0x114 ? kvm_make_vcpus_request_mask+0x174/0x440 [kvm] kasan_report+0x38/0x50 kasan_check_range+0xf5/0x1d0 kvm_make_vcpus_request_mask+0x174/0x440 [kvm] 0 [kvm] ? kvm_arch_exit+0x110/0x110 [kvm] ? sched_clock+0x5/0x10 ioapic_write_indirect+0x59f/0x9e0 [kvm] ? static_obj+0xc0/0xc0? __lock_acquired+0x1d2/0x8c0? kvm_ioapic_eoi_inject_work+0x120/0x120 [kvm] El problema parece ser que 'vcpu_bitmap' está asignado como un único largo en la pila y en realidad debería ser KVM_MAX_VCPUS largo. También parece que borramos los 16 bits inferiores con bitmap_zero() sin ningún motivo en particular (supongo que las variables 'bitmap' y 'vcpu_bitmap' en kvm_bitmap_or_dest_vcpus() causaron la confusión: mientras que la última tiene 16 bits de longitud , este último debería acomodar todas las vCPU posibles).

*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
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2024-05-21 CVE Reserved
  • 2024-05-21 CVE Published
  • 2024-05-22 EPSS Updated
  • 2024-12-19 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
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"
 >= 5.5 < 5.10.71
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.5 < 5.10.71"
en
Affected
Linux
Search vendor "Linux"
 Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
 >= 5.5 < 5.14.10
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.5 < 5.14.10"
en
Affected
Linux
Search vendor "Linux"
 Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
 >= 5.5 < 5.15
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.5 < 5.15"
en
Affected