[PATCH] bpf: verifier: avoid fall-through warnings

From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>, Lawrence Brakmo <brakmo@fb.com>
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	Kees Cook <keescook@chromium.org>
Subject: [PATCH] bpf: verifier: avoid fall-through warnings
Date: Tue, 11 Jun 2019 08:28:11 -0500	[thread overview]
Message-ID: <20190611132811.GA27212@embeddedor> (raw)

In preparation to enabling -Wimplicit-fallthrough, this patch silences
the following warning:

kernel/bpf/verifier.c: In function ‘check_return_code’:
kernel/bpf/verifier.c:5509:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG ||
      ^
kernel/bpf/verifier.c:5512:2: note: here
  case BPF_PROG_TYPE_CGROUP_SKB:
  ^~~~

Warning level 3 was used: -Wimplicit-fallthrough=3

Notice that it's much clearer to explicitly add breaks in each case
(that actually contains some code), rather than letting the code to
fall through.

This patch is part of the ongoing efforts to enable
-Wimplicit-fallthrough.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 kernel/bpf/verifier.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 1e9d10b32984..e9fc28991548 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5509,11 +5509,13 @@ static int check_return_code(struct bpf_verifier_env *env)
 		if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG ||
 		    env->prog->expected_attach_type == BPF_CGROUP_UDP6_RECVMSG)
 			range = tnum_range(1, 1);
+		break;
 	case BPF_PROG_TYPE_CGROUP_SKB:
 		if (env->prog->expected_attach_type == BPF_CGROUP_INET_EGRESS) {
 			range = tnum_range(0, 3);
 			enforce_attach_type_range = tnum_range(2, 3);
 		}
+		break;
 	case BPF_PROG_TYPE_CGROUP_SOCK:
 	case BPF_PROG_TYPE_SOCK_OPS:
 	case BPF_PROG_TYPE_CGROUP_DEVICE:
-- 
2.21.0

