Re: [PATCH v2 bpf-next 0/3] Fix BPF verifier global subprog context argument logic

Stanislav Fomichev
2023-02-16T17:40:53Z

On 02/15, Andrii Nakryiko wrote:
> Fix kernel bug in determining whether global subprog's argument is
> PTR_TO_CTX,
> which is done based on type names. Currently KPROBE programs are broken.

> Add few tests validating that KPROBE context can be passed to global
> subprog.
> For that also refactor test_global_funcs test to use test_loader
> framework.

> v1->v2:
> - fix compilation warning on arm64 and s390x by force-casting ctx to
> `void *`, to discard const from `const struct user_pt_regs *`, when
> passing it to bpf_get_stack().

Such a shame there isn't something like unconstify(typeof(xxx)) :-(
But thank you for catching this. Need to build a habit of looking at
the buildbot output.

Reposting for patchwork:

Acked-by: Stanislav Fomichev <sdf@google.com>

> Andrii Nakryiko (3):
> bpf: fix global subprog context argument resolution logic
> selftests/bpf: convert test_global_funcs test to test_loader framework
> selftests/bpf: add global subprog context passing tests

> kernel/bpf/btf.c | 13 +-
> .../bpf/prog_tests/test_global_funcs.c | 133 +++++-------------
> .../selftests/bpf/progs/test_global_func1.c | 6 +-
> .../selftests/bpf/progs/test_global_func10.c | 4 +-
> .../selftests/bpf/progs/test_global_func11.c | 4 +-
> .../selftests/bpf/progs/test_global_func12.c | 4 +-
> .../selftests/bpf/progs/test_global_func13.c | 4 +-
> .../selftests/bpf/progs/test_global_func14.c | 4 +-
> .../selftests/bpf/progs/test_global_func15.c | 4 +-
> .../selftests/bpf/progs/test_global_func16.c | 4 +-
> .../selftests/bpf/progs/test_global_func17.c | 4 +-
> .../selftests/bpf/progs/test_global_func2.c | 43 +++++-
> .../selftests/bpf/progs/test_global_func3.c | 10 +-
> .../selftests/bpf/progs/test_global_func4.c | 55 +++++++-
> .../selftests/bpf/progs/test_global_func5.c | 4 +-
> .../selftests/bpf/progs/test_global_func6.c | 4 +-
> .../selftests/bpf/progs/test_global_func7.c | 4 +-
> .../selftests/bpf/progs/test_global_func8.c | 4 +-
> .../selftests/bpf/progs/test_global_func9.c | 4 +-
> .../bpf/progs/test_global_func_ctx_args.c | 105 ++++++++++++++
> 20 files changed, 292 insertions(+), 125 deletions(-)
> create mode 100644
> tools/testing/selftests/bpf/progs/test_global_func_ctx_args.c

> --
> 2.30.2