bpf: zero extend the result of an arena 32-bit cmpxchg
- 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- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean?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 6.12.114, 6.18.57, 7.2.7
- 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
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: zero extend the result of an arena 32-bit cmpxchg bpf_convert_ctx_accesses() rewrites an atomic on an arena pointer from BPF_STX | BPF_ATOMIC to BPF_STX | BPF_PROBE_ATOMIC, and it runs before bpf_opt_subreg_zext_lo32_rnd_hi32(). That pass emits an explicit zero extension for a 32-bit cmpxchg even when bpf_jit_needs_zext() is false. This is done because on some architectures 32-bit cmpxchg requires explicit zero extension for the dst register. E.g. on x86-64 'lock cmpxchg' does not change the %eax if comparison is successful, while BPF semantics declare that each operation on a 32-bit register zero extends it's upper half. is_cmpxchg_insn() matches BPF_MODE == BPF_ATOMIC only, so an arena cmpxchg misses said zero extension adjustment. This patch adjusts is_cmpxchg_insn() to match BPF_PROBE_ATOMIC alongside BPF_ATOMIC.
Timeline
- CVE published
- Record last updated
Affected versions
- Linux Linux
From d503a04f8bc0c75dc9db9452d8cc79d748afb752 · fixed in 1bb1be18263995b159cf5afad3a05500ba6d2a7b; From d503a04f8bc0c75dc9db9452d8cc79d748afb752 · fixed in 6bb6ae5ab1beffda51dabf41612f501d07f10fc6; From d503a04f8bc0c75dc9db9452d8cc79d748afb752 · fixed in 1c1b476d43a8b6c9bc04600369dd8cc39950d98e; From d503a04f8bc0c75dc9db9452d8cc79d748afb752 · fixed in 4814ed6406f3493bd554ad046da5f7fc04833571
- Linux Linux
6.10
- KernelLinux
From 6.10.0 · fixed in 6.12.114; From 6.13.0 · fixed in 6.18.57; From 6.19.0 · fixed in 7.2.7