CVE-2026-98039

In the Linux kernel, the following vulnerability has been resolved:

bpf: Require MEM_PERCPU for percpu kptr stores

map_kptr_match_type() treats perm_flags as the set of register type flags

that a kptr field permits. Adding MEM_PERCPU to that set for

BPF_KPTR_PERCPU does not require the source register to carry it, however.

The subset test consequently accepts both a plain bpf_obj_new() allocation

and a referenced kernel pointer into a __percpu_kptr map field.

Loads from the field are always marked MEM_PERCPU. Consumers then treat the

stored value as the cookie returned by bpf_percpu_obj_new(): per-CPU pointer

helpers relocate it, and map teardown selects the per-CPU free path. A plain

allocation can therefore provide an arbitrary kernel read/write, while a

kernel pointer can be relocated into an invalid address or sent through a

missing destructor.

Require the source MEM_PERCPU flag to match the destination field kind.

This preserves valid bpf_percpu_obj_new() stores and rejects both the

program-BTF and kernel-BTF variants.