bpf: Fix masking negation logic upon negative dst register
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 4.14.233, 4.19.190, 4.21
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: partial
Summary
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.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- Linux Linux
From 4.14.113 · fixed in 4.14.233; From 4.19.19 · fixed in 4.19.190; From 4.20.6 · fixed in 4.21
- Linux Linux
5.0
References 7
git.kernel.org
- stable/c/4d542ddb88fb2f39bf7f14caa2902f3e8d06f6ba
- stable/c/0e2dfdc74a7f4036127356d42ea59388f153f42c
- stable/c/53e0db429b37a32b8fc706d0d90eb4583ad13848
- stable/c/2cfa537674cd1051a3b8111536d77d0558f33d5d
- stable/c/6eba92a4d4be8feb4dc33976abac544fa99d6ecc
- stable/c/7cf64d8679ca1cb20cf57d6a88bfee79a0922a66
- stable/c/b9b34ddbe2076ade359cd5ce7537d5ed019e9807