wireguard-linux/kernel/bpf/check_btf.c, branch davem/net

bpf: Apply CO-RE relocations before subprogram validation

2026-09-18T01:01:42Z

check_subprogs() verifies that each subprogram ends in an exit or an unconditional jump before in-kernel CO-RE relocations are applied. An unresolved relocation can then replace that terminal instruction with an invalid helper call. The resulting fall-through into another subprogram breaks the CFG invariant used by postorder and stack liveness analysis, which can write past their per-subprogram arrays. Apply CO-RE relocations immediately after preparing the program BTF, before subprogram discovery and validation. Keep func_info and line_info validation after subprogram discovery because those records depend on the complete subprogram layout. Reject an ldimm64 first slot at the end of the instruction stream before CO-RE can inspect its missing second slot. check_subprogs() previously rejected this form before relocation processing because it is not a valid subprogram terminator. Moving CO-RE ahead of check_subprogs() removes that implicit protection, so perform an explicit check before applying relocations. Include core_relo_cnt when deciding whether to prepare program BTF. A load that supplied only CO-RE relocation metadata previously skipped both BTF setup and relocation processing. Fixes: fbd94c7afcf9 ("bpf: Pass a set of bpf_core_relo-s to prog_load command.") Suggested-by: Andrii Nakryiko Suggested-by: Alexei Starovoitov Suggested-by: Eduard Zingerman Signed-off-by: Kumar Kartikeya Dwivedi Acked-by: Eduard Zingerman Link: https://patch.msgid.link/20260917233222.2542500-5-memxor@gmail.com Signed-off-by: Eduard Zingerman

bpf: Rename 'early' BTF checking as a preparation phase

2026-08-08T10:03:25Z

BTF processing is split around subprogram discovery. The first phase gets program BTF and imports func_info because a BTF-tagged exception callback may not be referenced by any instruction. Subprogram discovery needs this metadata to find it. The later phase validates func_info and line_info against the complete subprogram table and applies CO-RE relocations. This split breaks a real dependency cycle rather than merely running the same checks early. Rename bpf_check_btf_info_early() and check_btf_func_early() to preparation names that reflect this role. Add short call-site comments to make the two phases and their responsibilities clear. No functional change is intended. Signed-off-by: Kumar Kartikeya Dwivedi Reviewed-by: Amery Hung Link: https://patch.msgid.link/20260808003938.3486067-2-memxor@gmail.com Signed-off-by: Eduard Zingerman

bpf: Move BTF checking logic into check_btf.c

2026-04-12T19:37:04Z

BTF validation logic is independent from the main verifier. Move it into check_btf.c Acked-by: Kumar Kartikeya Dwivedi Acked-by: Daniel Borkmann Link: https://lore.kernel.org/r/20260412152936.54262-7-alexei.starovoitov@gmail.com Signed-off-by: Alexei Starovoitov