NetSight
IP …
high7.1

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 …

Impact

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 products

VendorProductAffected versions
LinuxLinux Kernel
from 4.14.113 before 4.14.233
from 4.19.19 before 4.19.190
from 5.0 before 5.4.117
from 5.5 before 5.10.35
from 5.11 before 5.11.19
from 5.12 before 5.12.2

References