Commit d0f01043 authored Nov 26, 2019 by Alexei Starovoitov Committed by Daniel Borkmann Nov 27, 2019

bpf: Fix static checker warning



kernel/bpf/btf.c:4023 btf_distill_func_proto()
        error: potentially dereferencing uninitialized 't'.

kernel/bpf/btf.c
  4012          nargs = btf_type_vlen(func);
  4013          if (nargs >= MAX_BPF_FUNC_ARGS) {
  4014                  bpf_log(log,
  4015                          "The function %s has %d arguments. Too many.\n",
  4016                          tname, nargs);
  4017                  return -EINVAL;
  4018          }
  4019          ret = __get_type_size(btf, func->type, &t);
                                                       ^^
t isn't initialized for the first -EINVAL return

This is unlikely path, since BTF should have been validated at this point.
Fix it by returning 'void' BTF.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191126230106.237179-1-ast@kernel.org

parent a95069ec

kernel/bpf/btf.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -3976,8 +3976,10 @@ static int __get_type_size(struct btf *btf, u32 btf_id,
		t = btf_type_by_id(btf, btf_id);
		while (t && btf_type_is_modifier(t))
		t = btf_type_by_id(btf, t->type);
		if (!t)
		if (!t) {
		*bad_type = btf->types[0];
		return -EINVAL;
		}
		if (btf_type_is_ptr(t))
		/* kernel size of pointer. Not BPF's size of pointer*/
		return sizeof(void *);

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