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Message-ID: <ZtllCZOrO9b-MDtE@google.com> Date: Thu, 5 Sep 2024 08:00:09 +0000 From: Matt Bobrowski <mattbobrowski@...gle.com> To: Shung-Hsi Yu <shung-hsi.yu@...e.com> Cc: Eduard Zingerman <eddyz87@...il.com>, bpf@...r.kernel.org, Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, Martin KaFai Lau <martin.lau@...ux.dev>, Song Liu <song@...nel.org>, Yonghong Song <yonghong.song@...ux.dev>, John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>, "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, David Vernet <void@...ifault.com>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, kernel test robot <lkp@...el.com> Subject: Re: [PATCH bpf-next] bpf: use type_may_be_null() helper for nullable-param check On Thu, Sep 05, 2024 at 01:52:32PM +0800, Shung-Hsi Yu wrote: > Commit 980ca8ceeae6 ("bpf: check bpf_dummy_struct_ops program params for > test runs") does bitwise AND between reg_type and PTR_MAYBE_NULL, which > is correct, but due to type difference the compiler complains: > > net/bpf/bpf_dummy_struct_ops.c:118:31: warning: bitwise operation between different enumeration types ('const enum bpf_reg_type' and 'enum bpf_type_flag') [-Wenum-enum-conversion] > 118 | if (info && (info->reg_type & PTR_MAYBE_NULL)) > | ~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~ > > Workaround the warning by moving the type_may_be_null() helper from > verifier.c into bpf_verifier.h, and reuse it here to check whether param > is nullable. > > Fixes: 980ca8ceeae6 ("bpf: check bpf_dummy_struct_ops program params for test runs") > Reported-by: kernel test robot <lkp@...el.com> > Closes: https://lore.kernel.org/oe-kbuild-all/202404241956.HEiRYwWq-lkp@intel.com/ > Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@...e.com> > --- > Due to kernel test bot not setting the correct email header > (reported[1]) Eduard probably never saw the report about the warning > (nor did it show up on Patchwork). > > 1: https://github.com/intel/lkp-tests/issues/383 > --- > include/linux/bpf_verifier.h | 5 +++++ > kernel/bpf/verifier.c | 5 ----- > net/bpf/bpf_dummy_struct_ops.c | 2 +- > 3 files changed, 6 insertions(+), 6 deletions(-) > > diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h > index 8458632824a4..4513372c5bc8 100644 > --- a/include/linux/bpf_verifier.h > +++ b/include/linux/bpf_verifier.h > @@ -927,6 +927,11 @@ static inline bool type_is_sk_pointer(enum bpf_reg_type type) > type == PTR_TO_XDP_SOCK; > } > > +static inline bool type_may_be_null(u32 type) > +{ > + return type & PTR_MAYBE_NULL; > +} > + > > static inline void mark_reg_scratched(struct bpf_verifier_env *env, u32 regno) > { > env->scratched_regs |= 1U << regno; > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index b806afeba212..53d0556fbbf3 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -383,11 +383,6 @@ static void verbose_invalid_scalar(struct bpf_verifier_env *env, > verbose(env, " should have been in [%d, %d]\n", range.minval, range.maxval); > } > > -static bool type_may_be_null(u32 type) > -{ > - return type & PTR_MAYBE_NULL; > -} > - > static bool reg_not_null(const struct bpf_reg_state *reg) > { > enum bpf_reg_type type; > diff --git a/net/bpf/bpf_dummy_struct_ops.c b/net/bpf/bpf_dummy_struct_ops.c > index 3ea52b05adfb..f71f67c6896b 100644 > --- a/net/bpf/bpf_dummy_struct_ops.c > +++ b/net/bpf/bpf_dummy_struct_ops.c > @@ -115,7 +115,7 @@ static int check_test_run_args(struct bpf_prog *prog, struct bpf_dummy_ops_test_ > > offset = btf_ctx_arg_offset(bpf_dummy_ops_btf, func_proto, arg_no); > info = find_ctx_arg_info(prog->aux, offset); > - if (info && (info->reg_type & PTR_MAYBE_NULL)) > + if (info && type_may_be_null(info->reg_type)) Maybe as part of this clean up, we should also consider replacing all the open-coded & PTR_MAYBE_NULL checks with type_may_be_null() which we have sprinkled throughout kernel/bpf/verifier.c? /M
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