Re: [PATCH 0/2] bpf: Build with -Wcast-function-type

On Mon, Sep 27, 2021 at 10:24 PM Andrii Nakryiko
[off-list ref] wrote:

On Mon, Sep 27, 2021 at 11:27 AM Kees Cook [off-list ref] wrote:

quoted

Hi,

In order to keep ahead of cases in the kernel where Control Flow Integrity
(CFI) may trip over function call casts, enabling -Wcast-function-type
is helpful. To that end, replace BPF_CAST_CALL() as it triggers warnings
with this option and is now one of the last places in the kernel in need
of fixing.

Thanks,

-Kees

Kees Cook (2):
  bpf: Replace "want address" users of BPF_CAST_CALL with BPF_CALL_IMM
  bpf: Replace callers of BPF_CAST_CALL with proper function typedef

Both patches look good to me. For the series:

Acked-by: Andrii Nakryiko <andrii@kernel.org>

It needs a rebase to bpf-next:
In file included from ../lib/test_bpf.c:12:
../lib/test_bpf.c: In function ‘prepare_tail_call_tests’:
../lib/test_bpf.c:12442:27: error: implicit declaration of function
‘BPF_CAST_CALL’; did you mean ‘BPF_EMIT_CALL’?
[-Werror=implicit-function-declaration]
     *insn = BPF_EMIT_CALL(BPF_CAST_CALL(addr));

Please mark the patches as [PATCH bpf-next v2] to help CI pick the right tree.