Description (CNA)
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.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected d503a04f8bc0c75dc9db9452d8cc79d748afb752 before 1bb1be18263995b159cf5afad3a05500ba6d2a7b; affected d503a04f8bc0c75dc9db9452d8cc79d748afb752 before 6bb6ae5ab1beffda51dabf41612f501d07f10fc6; affected d503a04f8bc0c75dc9db9452d8cc79d748afb752 before 1c1b476d43a8b6c9bc04600369dd8cc39950d98e; affected d503a04f8bc0c75dc9db9452d8cc79d748afb752 before 4814ed6406f3493bd554ad046da5f7fc04833571 |
| Linux / Linux | affected 6.10; unaffected 0 before 6.10; unaffected 6.12.114 through 6.12.*; unaffected 6.18.57 through 6.18.*; unaffected 7.2.7 through 7.2.*; unaffected 7.3 through * |
CWE
No CWE identifiers supplied.