[PATCH 5.9 209/757] libbpf: Fix unintentional success return code in bpf_object__load

[Greg Kroah-Hartman]

From: Alex Gartrell <alexgartrell@xxxxxxxxx>

[ Upstream commit ef05afa66c59c2031a3798916ef3ff3778232129 ]

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@xxxxxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20200826075549.1858580-1-alexgartrell@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 tools/lib/bpf/libbpf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e493d6048143f..8b71a31ca4a97 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -5425,7 +5425,7 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
 		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);
-- 
2.25.1