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Vulnerability · Published Feb 27, 2024 · Assigned by Linux

CVE-2021-46974bpf: Fix masking negation logic upon negative dst register

High 7.1

In plain English

A high-severity security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 16% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.1High
Exploit odds (30 days)0.2%top 83.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix masking negation logic upon negative dst register The negation logic for the case where the off_reg is sitting in the dst register is not correct given then we cannot just invert the add to a sub or vice versa. As a fix, perform the final bitwise and-op unconditionally into AX from the off_reg, then move the pointer from the src to dst and finally use AX as the source for the original pointer arithmetic operation such that the inversion yields a correct result. The single non-AX mov in between is possible given constant blinding is retaining it as it's not an immediate based operation.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux5.10.38-1DEBIAN-CVE-2021-46974
Debian:13linux5.10.38-1DEBIAN-CVE-2021-46974
Debian:14linux5.10.38-1DEBIAN-CVE-2021-46974
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2021-46974
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2021-46974
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2021-46974

Affected products (as reported)

VendorProductVersions
Linux Linux ae03b6b1c880a03d4771257336dc3bca156dd51b – before 4d542ddb88fb2f39bf7f14caa2902f3e8d06f6baf92a819b4cbef8c9527d9797110544b2055a4b96 – before 0e2dfdc74a7f4036127356d42ea59388f153f42c979d63d50c0c0f7bc537bf821e056cc9fe5abd38 – before 53e0db429b37a32b8fc706d0d90eb4583ad13848979d63d50c0c0f7bc537bf821e056cc9fe5abd38 – before 2cfa537674cd1051a3b8111536d77d0558f33d5d979d63d50c0c0f7bc537bf821e056cc9fe5abd38 – before 6eba92a4d4be8feb4dc33976abac544fa99d6ecc979d63d50c0c0f7bc537bf821e056cc9fe5abd38 – before 7cf64d8679ca1cb20cf57d6a88bfee79a0922a66979d63d50c0c0f7bc537bf821e056cc9fe5abd38 – before b9b34ddbe2076ade359cd5ce7537d5ed019e9807078da99d449f64ca04d459cdbdcce513b64173cd
Linux Linux 5.0

References