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From:   xiakaixu1987@gmail.com
To:     ast@kernel.org, daniel@iogearbox.net, kafai@fb.com,
        songliubraving@fb.com, yhs@fb.com, andrii@kernel.org,
        john.fastabend@gmail.com, kpsingh@chromium.org
Cc:     netdev@vger.kernel.org, bpf@vger.kernel.org,
        linux-kernel@vger.kernel.org, Kaixu Xia <kaixuxia@tencent.com>
Subject: [PATCH v2] bpf: Fix unsigned 'datasec_id' compared with zero in check_pseudo_btf_id
Date:   Wed, 11 Nov 2020 10:59:01 +0800
Message-Id: <1605063541-25424-1-git-send-email-kaixuxia@tencent.com>
Precedence: bulk

From: Kaixu Xia <kaixuxia@tencent.com>

The unsigned variable datasec_id is assigned a return value from the call
to check_pseudo_btf_id(), which may return negative error code.

Fixes coccicheck warning:

./kernel/bpf/verifier.c:9616:5-15: WARNING: Unsigned expression compared with zero: datasec_id > 0

Reported-by: Tosk Robot <tencent_os_robot@tencent.com>
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
---
v2:
 -split out datasec_id definition into a separate line.

 kernel/bpf/verifier.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 6200519582a6..3fea4fc04e94 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9572,7 +9572,8 @@ static int check_pseudo_btf_id(struct bpf_verifier_env *env,
 			       struct bpf_insn *insn,
 			       struct bpf_insn_aux_data *aux)
 {
-	u32 datasec_id, type, id = insn->imm;
+	s32 datasec_id;
+	u32 type, id = insn->imm;
 	const struct btf_var_secinfo *vsi;
 	const struct btf_type *datasec;
 	const struct btf_type *t;
-- 
2.20.0