# CVE-2021-46974: linux: In the Linux kernel, the following vulnerability has been resolved:  bpf: Fix masking negation logic upon negative ds...

CVE-2021-46974 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-46974, released February 27, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-46974
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0025
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 27, 2024

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.10.38-1 | [DEBIAN-CVE-2021-46974](https://patchblox.com/security/data/fix/linux/debian-cve-2021-46974.md) | Feb 27, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.10.38-1 | [DEBIAN-CVE-2021-46974](https://patchblox.com/security/data/fix/linux/debian-cve-2021-46974.md) | Feb 27, 2024 |
| Linux | linux Debian 14 | 5.10.38-1 | [DEBIAN-CVE-2021-46974](https://patchblox.com/security/data/fix/linux/debian-cve-2021-46974.md) | Feb 27, 2024 |

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