bpf: Fix unsigned 'datasec_id' compared with zero in check_pseudo_btf_id

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

This fixes the following coccicheck warning:

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

Fixes: 876b6eed9700 ("bpf: Introduce bpf_per_cpu_ptr()")
Reported-by: Tosk Robot <tencent_os_robot@tencent.com>
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Cc: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/bpf/1605071026-25906-1-git-send-email-kaixuxia@tencent.com

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 6200519582a64b671c15884f0c08932c18890c0a..6204ec705d809952e3c4a84ec1e7c68ee070b2a7 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9572,12 +9572,13 @@ 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;
        const struct btf_var_secinfo *vsi;
        const struct btf_type *datasec;
        const struct btf_type *t;
        const char *sym_name;
        bool percpu = false;
+       u32 type, id = insn->imm;
+       s32 datasec_id;
        u64 addr;
        int i;