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PUBLISHED

CVE-2021-46974

bpf: Fix masking negation logic upon negative dst register

Reserved:2024-02-27
Published:2024-02-27
Updated:2024-04-04

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.

Product status

Default status
unaffected

ae03b6b1c880 before 4d542ddb88fb
affected

f92a819b4cbe before 0e2dfdc74a7f
affected

979d63d50c0c before 53e0db429b37
affected

979d63d50c0c before 2cfa537674cd
affected

979d63d50c0c before 6eba92a4d4be
affected

979d63d50c0c before 7cf64d8679ca
affected

979d63d50c0c before b9b34ddbe207
affected

Default status
affected

5.0
affected

Any version before 5.0
unaffected

4.14.233
unaffected

4.19.190
unaffected

5.4.117
unaffected

5.10.35
unaffected

5.11.19
unaffected

5.12.2
unaffected

5.13
unaffected

References

https://git.kernel.org/stable/c/4d542ddb88fb2f39bf7f14caa2902f3e8d06f6ba

https://git.kernel.org/stable/c/0e2dfdc74a7f4036127356d42ea59388f153f42c

https://git.kernel.org/stable/c/53e0db429b37a32b8fc706d0d90eb4583ad13848

https://git.kernel.org/stable/c/2cfa537674cd1051a3b8111536d77d0558f33d5d

https://git.kernel.org/stable/c/6eba92a4d4be8feb4dc33976abac544fa99d6ecc

https://git.kernel.org/stable/c/7cf64d8679ca1cb20cf57d6a88bfee79a0922a66

https://git.kernel.org/stable/c/b9b34ddbe2076ade359cd5ce7537d5ed019e9807

cve.org CVE-2021-46974

nvd.nist.gov CVE-2021-46974

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