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Unrated severityNVD Advisory· Published Feb 27, 2024· Updated May 4, 2025

bpf: Fix masking negation logic upon negative dst register

CVE-2021-46974

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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Affected products

91

Patches

Vulnerability mechanics

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