CVE-2022-48929: bpf: Fix crash due to out of bounds access into reg2btf_ids.

Vulnerability summary

CVE-2022-48929 is a medium (CVSS 5.5) Out-of-bounds Read vulnerability in linux. EPSS estimates a 0.21% chance of exploitation in the next 30 days, higher than 11.2% of scored vulnerabilities.

Timeline

1. 22-08-2024
   PublishedVulnerability first disclosed.
2. 11-05-2026
   Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix crash due to out of bounds access into reg2btf_ids. When commit e6ac2450d6de ("bpf: Support bpf program calling kernel function") added kfunc support, it defined reg2btf_ids as a cheap way to translate the verifier reg type to the appropriate btf_vmlinux BTF ID, however commit c25b2ae13603 ("bpf: Replace PTR_TO_XXX_OR_NULL with PTR_TO_XXX | PTR_MAYBE_NULL") moved the __BPF_REG_TYPE_MAX from the last member of bpf_reg_type enum to after the base register types, and defined other variants using type flag composition. However, now, the direct usage of reg->type to index into reg2btf_ids may no longer fall into __BPF_REG_TYPE_MAX range, and hence lead to out of bounds access and kernel crash on dereference of bad pointer.

• CWE-125Out-of-bounds ReadThe product reads data past the end, or before the beginning, of the intended buffer.