CVE Vulnerabilities

CVE-2020-11884

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Published: Apr 29, 2020 | Modified: Nov 07, 2023
CVSS 3.x
7
HIGH
Source:
NVD
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 2.x
6.9 MEDIUM
AV:L/AC:M/Au:N/C:C/I:C/A:C
RedHat/V2
RedHat/V3
7 IMPORTANT
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Ubuntu
HIGH

In the Linux kernel 4.19 through 5.6.7 on the s390 platform, code execution may occur because of a race condition, as demonstrated by code in enable_sacf_uaccess in arch/s390/lib/uaccess.c that fails to protect against a concurrent page table upgrade, aka CID-3f777e19d171. A crash could also occur.

Weakness

The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently.

Affected Software

Name Vendor Start Version End Version
Linux_kernel Linux 4.15 (including) 4.19.119 (excluding)
Linux_kernel Linux 4.20 (including) 5.4.36 (excluding)
Linux_kernel Linux 5.5 (including) 5.6.8 (excluding)
Red Hat Enterprise Linux 8 RedHat kernel-0:4.18.0-193.1.2.el8_2 *
Red Hat Enterprise Linux 8.0 Update Services for SAP Solutions RedHat kernel-0:4.18.0-80.23.2.el8_0 *
Red Hat Enterprise Linux 8.1 Extended Update Support RedHat kernel-0:4.18.0-147.13.2.el8_1 *
Linux Ubuntu bionic *
Linux Ubuntu eoan *
Linux Ubuntu focal *
Linux Ubuntu upstream *
Linux-aws Ubuntu upstream *
Linux-aws-5.0 Ubuntu upstream *
Linux-aws-5.15 Ubuntu upstream *
Linux-aws-5.3 Ubuntu bionic *
Linux-aws-5.3 Ubuntu upstream *
Linux-aws-5.4 Ubuntu upstream *
Linux-aws-fips Ubuntu fips-updates/bionic *
Linux-aws-fips Ubuntu fips/bionic *
Linux-aws-fips Ubuntu trusty *
Linux-aws-fips Ubuntu upstream *
Linux-aws-fips Ubuntu xenial *
Linux-aws-hwe Ubuntu upstream *
Linux-azure Ubuntu trusty *
Linux-azure Ubuntu upstream *
Linux-azure-4.15 Ubuntu bionic *
Linux-azure-4.15 Ubuntu upstream *
Linux-azure-5.15 Ubuntu upstream *
Linux-azure-5.3 Ubuntu upstream *
Linux-azure-5.4 Ubuntu upstream *
Linux-azure-edge Ubuntu upstream *
Linux-azure-fde Ubuntu focal *
Linux-azure-fde Ubuntu upstream *
Linux-azure-fde-5.15 Ubuntu upstream *
Linux-azure-fips Ubuntu fips-updates/bionic *
Linux-azure-fips Ubuntu fips/bionic *
Linux-azure-fips Ubuntu trusty *
Linux-azure-fips Ubuntu upstream *
Linux-azure-fips Ubuntu xenial *
Linux-bluefield Ubuntu upstream *
Linux-fips Ubuntu fips-updates/bionic *
Linux-fips Ubuntu fips/bionic *
Linux-fips Ubuntu upstream *
Linux-gcp Ubuntu upstream *
Linux-gcp-4.15 Ubuntu upstream *
Linux-gcp-5.15 Ubuntu upstream *
Linux-gcp-5.3 Ubuntu upstream *
Linux-gcp-5.4 Ubuntu upstream *
Linux-gcp-edge Ubuntu upstream *
Linux-gcp-fips Ubuntu fips/bionic *
Linux-gcp-fips Ubuntu trusty *
Linux-gcp-fips Ubuntu upstream *
Linux-gcp-fips Ubuntu xenial *
Linux-gke Ubuntu focal *
Linux-gke Ubuntu upstream *
Linux-gke Ubuntu xenial *
Linux-gke-4.15 Ubuntu upstream *
Linux-gke-5.0 Ubuntu upstream *
Linux-gke-5.3 Ubuntu upstream *
Linux-gkeop Ubuntu upstream *
Linux-gkeop-5.15 Ubuntu upstream *
Linux-hwe Ubuntu bionic *
Linux-hwe Ubuntu upstream *
Linux-hwe Ubuntu xenial *
Linux-hwe-5.15 Ubuntu upstream *
Linux-hwe-5.4 Ubuntu upstream *
Linux-hwe-6.8 Ubuntu upstream *
Linux-hwe-edge Ubuntu bionic *
Linux-hwe-edge Ubuntu esm-infra/bionic *
Linux-hwe-edge Ubuntu esm-infra/xenial *
Linux-hwe-edge Ubuntu upstream *
Linux-hwe-edge Ubuntu xenial *
Linux-ibm Ubuntu upstream *
Linux-ibm-5.15 Ubuntu upstream *
Linux-ibm-5.4 Ubuntu upstream *
Linux-intel Ubuntu upstream *
Linux-intel-iot-realtime Ubuntu upstream *
Linux-intel-iotg Ubuntu upstream *
Linux-intel-iotg-5.15 Ubuntu upstream *
Linux-iot Ubuntu upstream *
Linux-kvm Ubuntu upstream *
Linux-lowlatency Ubuntu upstream *
Linux-lowlatency-hwe-5.15 Ubuntu upstream *
Linux-lowlatency-hwe-6.8 Ubuntu upstream *
Linux-lts-trusty Ubuntu upstream *
Linux-lts-xenial Ubuntu upstream *
Linux-nvidia Ubuntu upstream *
Linux-nvidia-6.5 Ubuntu upstream *
Linux-nvidia-6.8 Ubuntu upstream *
Linux-nvidia-lowlatency Ubuntu upstream *
Linux-oem Ubuntu upstream *
Linux-oem-5.6 Ubuntu upstream *
Linux-oem-6.8 Ubuntu upstream *
Linux-oem-osp1 Ubuntu upstream *
Linux-oracle Ubuntu upstream *
Linux-oracle-5.0 Ubuntu upstream *
Linux-oracle-5.15 Ubuntu upstream *
Linux-oracle-5.3 Ubuntu upstream *
Linux-oracle-5.4 Ubuntu upstream *
Linux-raspi Ubuntu upstream *
Linux-raspi-5.4 Ubuntu upstream *
Linux-raspi-realtime Ubuntu upstream *
Linux-raspi2 Ubuntu upstream *
Linux-raspi2-5.3 Ubuntu upstream *
Linux-realtime Ubuntu jammy *
Linux-realtime Ubuntu upstream *
Linux-riscv Ubuntu jammy *
Linux-riscv Ubuntu upstream *
Linux-riscv-5.15 Ubuntu upstream *
Linux-riscv-6.8 Ubuntu upstream *
Linux-snapdragon Ubuntu upstream *
Linux-xilinx-zynqmp Ubuntu upstream *

Extended Description

This can have security implications when the expected synchronization is in security-critical code, such as recording whether a user is authenticated or modifying important state information that should not be influenced by an outsider. A race condition occurs within concurrent environments, and is effectively a property of a code sequence. Depending on the context, a code sequence may be in the form of a function call, a small number of instructions, a series of program invocations, etc. A race condition violates these properties, which are closely related:

A race condition exists when an “interfering code sequence” can still access the shared resource, violating exclusivity. Programmers may assume that certain code sequences execute too quickly to be affected by an interfering code sequence; when they are not, this violates atomicity. For example, the single “x++” statement may appear atomic at the code layer, but it is actually non-atomic at the instruction layer, since it involves a read (the original value of x), followed by a computation (x+1), followed by a write (save the result to x). The interfering code sequence could be “trusted” or “untrusted.” A trusted interfering code sequence occurs within the product; it cannot be modified by the attacker, and it can only be invoked indirectly. An untrusted interfering code sequence can be authored directly by the attacker, and typically it is external to the vulnerable product.

Potential Mitigations

  • Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring.
  • Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).

References