CVE Vulnerabilities

CVE-2021-28038

Allocation of Resources Without Limits or Throttling

Published: Mar 05, 2021 | Modified: Mar 25, 2024
CVSS 3.x
6.5
MEDIUM
Source:
NVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
CVSS 2.x
4.9 MEDIUM
AV:L/AC:L/Au:N/C:N/I:N/A:C
RedHat/V2
RedHat/V3
Ubuntu
MEDIUM

An issue was discovered in the Linux kernel through 5.11.3, as used with Xen PV. A certain part of the netback driver lacks necessary treatment of errors such as failed memory allocations (as a result of changes to the handling of grant mapping errors). A host OS denial of service may occur during misbehavior of a networking frontend driver. NOTE: this issue exists because of an incomplete fix for CVE-2021-26931.

Weakness

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor.

Affected Software

Name Vendor Start Version End Version
Linux_kernel Linux 2.6.39 (including) 4.4.260 (excluding)
Linux_kernel Linux 4.5.0 (including) 4.9.260 (excluding)
Linux_kernel Linux 4.10.0 (including) 4.14.224 (excluding)
Linux_kernel Linux 4.15.0 (including) 4.19.179 (excluding)
Linux_kernel Linux 4.20.0 (including) 5.4.103 (excluding)
Linux_kernel Linux 5.10.0 (including) 5.10.21 (excluding)
Linux_kernel Linux 5.11.0 (including) 5.11.4 (excluding)
Linux_kernel Linux 5.12-rc1 (including) 5.12-rc1 (including)
Linux_kernel Linux 5.12-rc2 (including) 5.12-rc2 (including)
Linux Ubuntu bionic *
Linux Ubuntu esm-infra-legacy/trusty *
Linux Ubuntu focal *
Linux Ubuntu groovy *
Linux Ubuntu precise/esm *
Linux Ubuntu trusty *
Linux Ubuntu trusty/esm *
Linux Ubuntu upstream *
Linux Ubuntu xenial *
Linux-allwinner Ubuntu upstream *
Linux-allwinner-5.19 Ubuntu upstream *
Linux-aws Ubuntu bionic *
Linux-aws Ubuntu focal *
Linux-aws Ubuntu groovy *
Linux-aws Ubuntu trusty *
Linux-aws Ubuntu trusty/esm *
Linux-aws Ubuntu upstream *
Linux-aws Ubuntu xenial *
Linux-aws-5.0 Ubuntu bionic *
Linux-aws-5.0 Ubuntu esm-infra/bionic *
Linux-aws-5.0 Ubuntu upstream *
Linux-aws-5.11 Ubuntu upstream *
Linux-aws-5.13 Ubuntu upstream *
Linux-aws-5.15 Ubuntu upstream *
Linux-aws-5.19 Ubuntu upstream *
Linux-aws-5.3 Ubuntu bionic *
Linux-aws-5.3 Ubuntu esm-infra/bionic *
Linux-aws-5.3 Ubuntu upstream *
Linux-aws-5.4 Ubuntu bionic *
Linux-aws-5.4 Ubuntu upstream *
Linux-aws-5.8 Ubuntu upstream *
Linux-aws-6.2 Ubuntu upstream *
Linux-aws-6.5 Ubuntu upstream *
Linux-aws-6.8 Ubuntu upstream *
Linux-aws-fips Ubuntu fips-updates/bionic *
Linux-aws-fips Ubuntu fips-updates/focal *
Linux-aws-fips Ubuntu fips/bionic *
Linux-aws-fips Ubuntu fips/focal *
Linux-aws-fips Ubuntu trusty *
Linux-aws-fips Ubuntu upstream *
Linux-aws-fips Ubuntu xenial *
Linux-aws-hwe Ubuntu esm-infra/xenial *
Linux-aws-hwe Ubuntu upstream *
Linux-aws-hwe Ubuntu xenial *
Linux-azure Ubuntu bionic *
Linux-azure Ubuntu esm-infra/bionic *
Linux-azure Ubuntu esm-infra/xenial *
Linux-azure Ubuntu focal *
Linux-azure Ubuntu groovy *
Linux-azure Ubuntu trusty *
Linux-azure Ubuntu trusty/esm *
Linux-azure Ubuntu upstream *
Linux-azure Ubuntu xenial *
Linux-azure-4.15 Ubuntu bionic *
Linux-azure-4.15 Ubuntu upstream *
Linux-azure-5.11 Ubuntu upstream *
Linux-azure-5.13 Ubuntu upstream *
Linux-azure-5.15 Ubuntu upstream *
Linux-azure-5.19 Ubuntu upstream *
Linux-azure-5.3 Ubuntu bionic *
Linux-azure-5.3 Ubuntu esm-infra/bionic *
Linux-azure-5.3 Ubuntu upstream *
Linux-azure-5.4 Ubuntu bionic *
Linux-azure-5.4 Ubuntu upstream *
Linux-azure-5.8 Ubuntu upstream *
Linux-azure-6.2 Ubuntu upstream *
Linux-azure-6.5 Ubuntu upstream *
Linux-azure-6.8 Ubuntu upstream *
Linux-azure-edge Ubuntu bionic *
Linux-azure-edge Ubuntu esm-infra/bionic *
Linux-azure-edge Ubuntu upstream *
Linux-azure-fde Ubuntu focal *
Linux-azure-fde Ubuntu upstream *
Linux-azure-fde-5.15 Ubuntu upstream *
Linux-azure-fde-5.19 Ubuntu upstream *
Linux-azure-fde-6.2 Ubuntu upstream *
Linux-azure-fips Ubuntu fips-updates/bionic *
Linux-azure-fips Ubuntu fips-updates/focal *
Linux-azure-fips Ubuntu fips/bionic *
Linux-azure-fips Ubuntu fips/focal *
Linux-azure-fips Ubuntu trusty *
Linux-azure-fips Ubuntu upstream *
Linux-azure-fips Ubuntu xenial *
Linux-bluefield Ubuntu focal *
Linux-bluefield Ubuntu upstream *
Linux-dell300x Ubuntu bionic *
Linux-dell300x Ubuntu upstream *
Linux-fips Ubuntu fips-updates/bionic *
Linux-fips Ubuntu fips-updates/xenial *
Linux-fips Ubuntu fips/bionic *
Linux-fips Ubuntu fips/focal *
Linux-fips Ubuntu fips/xenial *
Linux-fips Ubuntu upstream *
Linux-gcp Ubuntu bionic *
Linux-gcp Ubuntu esm-infra/bionic *
Linux-gcp Ubuntu esm-infra/xenial *
Linux-gcp Ubuntu focal *
Linux-gcp Ubuntu groovy *
Linux-gcp Ubuntu upstream *
Linux-gcp Ubuntu xenial *
Linux-gcp-4.15 Ubuntu bionic *
Linux-gcp-4.15 Ubuntu upstream *
Linux-gcp-5.11 Ubuntu upstream *
Linux-gcp-5.13 Ubuntu upstream *
Linux-gcp-5.15 Ubuntu upstream *
Linux-gcp-5.19 Ubuntu upstream *
Linux-gcp-5.3 Ubuntu bionic *
Linux-gcp-5.3 Ubuntu esm-infra/bionic *
Linux-gcp-5.3 Ubuntu upstream *
Linux-gcp-5.4 Ubuntu bionic *
Linux-gcp-5.4 Ubuntu upstream *
Linux-gcp-5.8 Ubuntu upstream *
Linux-gcp-6.2 Ubuntu upstream *
Linux-gcp-6.5 Ubuntu upstream *
Linux-gcp-6.8 Ubuntu upstream *
Linux-gcp-edge Ubuntu bionic *
Linux-gcp-edge Ubuntu esm-infra/bionic *
Linux-gcp-edge Ubuntu upstream *
Linux-gcp-fips Ubuntu fips-updates/focal *
Linux-gcp-fips Ubuntu fips/bionic *
Linux-gcp-fips Ubuntu fips/focal *
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 bionic *
Linux-gke-4.15 Ubuntu esm-infra/bionic *
Linux-gke-4.15 Ubuntu upstream *
Linux-gke-5.0 Ubuntu bionic *
Linux-gke-5.0 Ubuntu upstream *
Linux-gke-5.15 Ubuntu upstream *
Linux-gke-5.3 Ubuntu bionic *
Linux-gke-5.3 Ubuntu upstream *
Linux-gke-5.4 Ubuntu bionic *
Linux-gke-5.4 Ubuntu upstream *
Linux-gkeop Ubuntu focal *
Linux-gkeop Ubuntu upstream *
Linux-gkeop-5.15 Ubuntu upstream *
Linux-gkeop-5.4 Ubuntu bionic *
Linux-gkeop-5.4 Ubuntu upstream *
Linux-hwe Ubuntu bionic *
Linux-hwe Ubuntu esm-infra/bionic *
Linux-hwe Ubuntu esm-infra/xenial *
Linux-hwe Ubuntu upstream *
Linux-hwe Ubuntu xenial *
Linux-hwe-5.11 Ubuntu upstream *
Linux-hwe-5.13 Ubuntu upstream *
Linux-hwe-5.15 Ubuntu upstream *
Linux-hwe-5.19 Ubuntu upstream *
Linux-hwe-5.4 Ubuntu bionic *
Linux-hwe-5.4 Ubuntu upstream *
Linux-hwe-5.8 Ubuntu focal *
Linux-hwe-5.8 Ubuntu upstream *
Linux-hwe-6.2 Ubuntu upstream *
Linux-hwe-6.5 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-5.13 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 bionic *
Linux-kvm Ubuntu focal *
Linux-kvm Ubuntu groovy *
Linux-kvm Ubuntu upstream *
Linux-kvm Ubuntu xenial *
Linux-laptop Ubuntu upstream *
Linux-lowlatency Ubuntu upstream *
Linux-lowlatency-hwe-5.15 Ubuntu upstream *
Linux-lowlatency-hwe-5.19 Ubuntu upstream *
Linux-lowlatency-hwe-6.2 Ubuntu upstream *
Linux-lowlatency-hwe-6.5 Ubuntu upstream *
Linux-lowlatency-hwe-6.8 Ubuntu upstream *
Linux-lts-trusty Ubuntu precise/esm *
Linux-lts-trusty Ubuntu upstream *
Linux-lts-xenial Ubuntu trusty *
Linux-lts-xenial Ubuntu trusty/esm *
Linux-lts-xenial Ubuntu upstream *
Linux-nvidia Ubuntu upstream *
Linux-nvidia-6.2 Ubuntu upstream *
Linux-nvidia-6.5 Ubuntu upstream *
Linux-nvidia-6.8 Ubuntu upstream *
Linux-nvidia-lowlatency Ubuntu upstream *
Linux-oem Ubuntu bionic *
Linux-oem Ubuntu esm-infra/bionic *
Linux-oem Ubuntu upstream *
Linux-oem Ubuntu xenial *
Linux-oem-5.10 Ubuntu focal *
Linux-oem-5.10 Ubuntu upstream *
Linux-oem-5.13 Ubuntu upstream *
Linux-oem-5.14 Ubuntu upstream *
Linux-oem-5.17 Ubuntu upstream *
Linux-oem-5.6 Ubuntu focal *
Linux-oem-5.6 Ubuntu upstream *
Linux-oem-6.0 Ubuntu upstream *
Linux-oem-6.1 Ubuntu upstream *
Linux-oem-6.11 Ubuntu upstream *
Linux-oem-6.5 Ubuntu upstream *
Linux-oem-6.8 Ubuntu upstream *
Linux-oem-osp1 Ubuntu bionic *
Linux-oem-osp1 Ubuntu upstream *
Linux-oracle Ubuntu bionic *
Linux-oracle Ubuntu esm-infra/xenial *
Linux-oracle Ubuntu focal *
Linux-oracle Ubuntu groovy *
Linux-oracle Ubuntu upstream *
Linux-oracle Ubuntu xenial *
Linux-oracle-5.0 Ubuntu bionic *
Linux-oracle-5.0 Ubuntu esm-infra/bionic *
Linux-oracle-5.0 Ubuntu upstream *
Linux-oracle-5.11 Ubuntu upstream *
Linux-oracle-5.13 Ubuntu upstream *
Linux-oracle-5.15 Ubuntu upstream *
Linux-oracle-5.3 Ubuntu bionic *
Linux-oracle-5.3 Ubuntu esm-infra/bionic *
Linux-oracle-5.3 Ubuntu upstream *
Linux-oracle-5.4 Ubuntu bionic *
Linux-oracle-5.4 Ubuntu upstream *
Linux-oracle-5.8 Ubuntu upstream *
Linux-oracle-6.5 Ubuntu upstream *
Linux-oracle-6.8 Ubuntu upstream *
Linux-raspi Ubuntu focal *
Linux-raspi Ubuntu groovy *
Linux-raspi Ubuntu upstream *
Linux-raspi-5.4 Ubuntu bionic *
Linux-raspi-5.4 Ubuntu upstream *
Linux-raspi-realtime Ubuntu upstream *
Linux-raspi2 Ubuntu bionic *
Linux-raspi2 Ubuntu focal *
Linux-raspi2 Ubuntu upstream *
Linux-raspi2 Ubuntu xenial *
Linux-raspi2-5.3 Ubuntu bionic *
Linux-raspi2-5.3 Ubuntu upstream *
Linux-realtime Ubuntu jammy *
Linux-realtime Ubuntu upstream *
Linux-riscv Ubuntu focal *
Linux-riscv Ubuntu groovy *
Linux-riscv Ubuntu upstream *
Linux-riscv-5.11 Ubuntu upstream *
Linux-riscv-5.15 Ubuntu upstream *
Linux-riscv-5.19 Ubuntu upstream *
Linux-riscv-5.8 Ubuntu focal *
Linux-riscv-5.8 Ubuntu upstream *
Linux-riscv-6.5 Ubuntu upstream *
Linux-riscv-6.8 Ubuntu upstream *
Linux-snapdragon Ubuntu bionic *
Linux-snapdragon Ubuntu upstream *
Linux-snapdragon Ubuntu xenial *
Linux-starfive Ubuntu upstream *
Linux-starfive-5.19 Ubuntu upstream *
Linux-starfive-6.2 Ubuntu upstream *
Linux-starfive-6.5 Ubuntu upstream *
Linux-xilinx-zynqmp Ubuntu upstream *

Extended Description

Code frequently has to work with limited resources, so programmers must be careful to ensure that resources are not consumed too quickly, or too easily. Without use of quotas, resource limits, or other protection mechanisms, it can be easy for an attacker to consume many resources by rapidly making many requests, or causing larger resources to be used than is needed. When too many resources are allocated, or if a single resource is too large, then it can prevent the code from working correctly, possibly leading to a denial of service.

Potential Mitigations

  • Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.

  • When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”

  • Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

  • Mitigation of resource exhaustion attacks requires that the target system either:

  • The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.

  • The second solution can be difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply requires more resources on the part of the attacker.

  • If the program must fail, ensure that it fails gracefully (fails closed). There may be a temptation to simply let the program fail poorly in cases such as low memory conditions, but an attacker may be able to assert control before the software has fully exited. Alternately, an uncontrolled failure could cause cascading problems with other downstream components; for example, the program could send a signal to a downstream process so the process immediately knows that a problem has occurred and has a better chance of recovery.

  • Ensure that all failures in resource allocation place the system into a safe posture.

  • Use resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems.

  • When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users.

  • Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).

References