bpf: Require MEM_PERCPU for percpu kptr stores

Summary

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.

Timeline

1. Sep 25, 2026, 10:23 AM UTCCVE published
2. Oct 19, 2026, 9:12 AM UTCRecord last updated

Affected versions

• Linux Linux

  From 36d8bdf75a93190e5669b9d1d95994e13e15ba1d · fixed in aaa9cf7707d1c5c0d2ca9d40c8b71652ac1c3c3f; From 36d8bdf75a93190e5669b9d1d95994e13e15ba1d · fixed in 0bdd6121c8dd5f1764efe701ce26bb8e15acb172; From 36d8bdf75a93190e5669b9d1d95994e13e15ba1d · fixed in ad4ebae5dbc2d47b544aa54f03c12490065be08a; From 36d8bdf75a93190e5669b9d1d95994e13e15ba1d · fixed in 048029ba1c793f8cabc4ad5eea765da01903f8f1

• Linux Linux

  6.7

• KernelLinux

  From 6.7.0 · fixed in 6.12.111; From 6.13.0 · fixed in 6.18.53; From 6.19.0 · fixed in 7.2.7

References 4