Out-of-bounds Read Affecting kernel-core package, versions *

Note: Versions mentioned in the description apply only to the upstream kernel-core package and not the kernel-core package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

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.

• https://access.redhat.com/security/cve/CVE-2022-48929
• https://git.kernel.org/stable/c/45ce4b4f9009102cd9f581196d480a59208690c1
• https://git.kernel.org/stable/c/8c39925e98d498b9531343066ef82ae39e41adae
• https://git.kernel.org/stable/c/f0ce1bc9e0235dd7412240be493d7ea65ed9eadc