libbpf: Fix unintentional success return code in bpf_object__load

There are code paths where EINVAL is returned directly without setting
errno. In that case, errno could be 0, which would mask the
failure. For example, if a careless programmer set log_level to 10000
out of laziness, they would have to spend a long time trying to figure
out why.

Fixes: 4f33ddb4e3e2 ("libbpf: Propagate EPERM to caller on program load")
Signed-off-by: Alex Gartrell <alexgartrell@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200826075549.1858580-1-alexgartrell@gmail.com

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 2e2523d8bb6d2dd045f69298a9cb63fc00bac5cd..8f9e7d281225c8796fed106fd273a40e2e6ec7e3 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -6067,7 +6067,7 @@ retry_load:
                free(log_buf);
                goto retry_load;
        }
-       ret = -errno;
+       ret = errno ? -errno : -LIBBPF_ERRNO__LOAD;
        cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
        pr_warn("load bpf program failed: %s\n", cp);
        pr_perm_msg(ret);