libbf: Fix uninitialized pointer at btf__parse_raw()

Recently, from commit d1714140867a ("libbpf: Add btf__parse_raw() and
generic btf__parse() APIs"), new API has been added to libbpf that
allows to parse BTF from raw data file (btf__parse_raw()).

The commit derives build failure of samples/bpf due to improper access
of uninitialized pointer at btf_parse_raw().

    btf.c: In function btf__parse_raw:
    btf.c:625:28: error: btf may be used uninitialized in this function
      625 |  return err ? ERR_PTR(err) : btf;
          |         ~~~~~~~~~~~~~~~~~~~^~~~~

This commit fixes the build failure of samples/bpf by adding code of
initializing btf pointer as NULL.

Fixes: d1714140867a ("libbpf: Add btf__parse_raw() and generic btf__parse() APIs")
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200805223359.32109-1-danieltimlee@gmail.com

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 856b09a045637ba50ef4f5b21c902a589d94f8de..4843e44916f7c454939ba0c32b174ac3ab077efa 100644 (file)
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -564,8 +564,8 @@ done:
 
 struct btf *btf__parse_raw(const char *path)
 {
+       struct btf *btf = NULL;
        void *data = NULL;
-       struct btf *btf;
        FILE *f = NULL;
        __u16 magic;
        int err = 0;