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From: Lorenz Bauer <lmb@cloudflare.com>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>
Cc: kernel-team@cloudflare.com, Lorenz Bauer <lmb@cloudflare.com>,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH bpf-next] bpf: explicitly size compatible_reg_types
Date: Wed, 23 Sep 2020 17:01:55 +0100	[thread overview]
Message-ID: <20200923160156.80814-1-lmb@cloudflare.com> (raw)

Arrays with designated initializers have an implicit length of the highest
initialized value plus one. I used this to ensure that newly added entries
in enum bpf_reg_type get a NULL entry in compatible_reg_types.

This is difficult to understand since it requires knowledge of the
peculiarities of designated initializers. Use __BPF_ARG_TYPE_MAX to size
the array instead.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Suggested-by: Alexei Starovoitov <ast@kernel.org>
---
 kernel/bpf/verifier.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 15ab889b0a3f..d7c993ded26a 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4002,7 +4002,7 @@ static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_T
 static const struct bpf_reg_types btf_ptr_types = { .types = { PTR_TO_BTF_ID } };
 static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALUE } };
 
-static const struct bpf_reg_types *compatible_reg_types[] = {
+static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
 	[ARG_PTR_TO_MAP_KEY]		= &map_key_value_types,
 	[ARG_PTR_TO_MAP_VALUE]		= &map_key_value_types,
 	[ARG_PTR_TO_UNINIT_MAP_VALUE]	= &map_key_value_types,
@@ -4025,7 +4025,6 @@ static const struct bpf_reg_types *compatible_reg_types[] = {
 	[ARG_PTR_TO_ALLOC_MEM_OR_NULL]	= &alloc_mem_types,
 	[ARG_PTR_TO_INT]		= &int_ptr_types,
 	[ARG_PTR_TO_LONG]		= &int_ptr_types,
-	[__BPF_ARG_TYPE_MAX]		= NULL,
 };
 
 static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
-- 
2.25.1


             reply	other threads:[~2020-09-23 16:02 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-23 16:01 Lorenz Bauer [this message]
2020-09-23 16:05 ` [PATCH bpf-next] bpf: explicitly size compatible_reg_types Andrii Nakryiko
2020-09-23 18:49   ` Alexei Starovoitov

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