CVE-2021-46974

MEDIUM
Published Feb 27, 2024 Modified Jan 9, 2025

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.

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CVSS v3.1 Score

5.5
MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected Products

Vendor Product
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel

References

Advisories & Patches

https://git.kernel.org/stable/c/0e2dfdc74a7f4036127356d42ea59388f153f42c https://git.kernel.org/stable/c/2cfa537674cd1051a3b8111536d77d0558f33d5d https://git.kernel.org/stable/c/4d542ddb88fb2f39bf7f14caa2902f3e8d06f6ba https://git.kernel.org/stable/c/53e0db429b37a32b8fc706d0d90eb4583ad13848 https://git.kernel.org/stable/c/6eba92a4d4be8feb4dc33976abac544fa99d6ecc https://git.kernel.org/stable/c/7cf64d8679ca1cb20cf57d6a88bfee79a0922a66 https://git.kernel.org/stable/c/b9b34ddbe2076ade359cd5ce7537d5ed019e9807 https://git.kernel.org/stable/c/0e2dfdc74a7f4036127356d42ea59388f153f42c https://git.kernel.org/stable/c/2cfa537674cd1051a3b8111536d77d0558f33d5d https://git.kernel.org/stable/c/4d542ddb88fb2f39bf7f14caa2902f3e8d06f6ba https://git.kernel.org/stable/c/53e0db429b37a32b8fc706d0d90eb4583ad13848 https://git.kernel.org/stable/c/6eba92a4d4be8feb4dc33976abac544fa99d6ecc https://git.kernel.org/stable/c/7cf64d8679ca1cb20cf57d6a88bfee79a0922a66 https://git.kernel.org/stable/c/b9b34ddbe2076ade359cd5ce7537d5ed019e9807

Frequently Asked Questions

What is CVE-2021-46974? +
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. It has a CVSS v3.1 base score of 5.5 (MEDIUM).
How severe is CVE-2021-46974? +
CVE-2021-46974 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.
What products are affected by CVE-2021-46974? +
CVE-2021-46974 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2021-46974? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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