linux-kernel - [PATCH 5.9 209/757] libbpf: Fix unintentional success return code in bpf_object_

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Date:   Tue, 27 Oct 2020 14:47:39 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alex Gartrell <alexgartrell@...il.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.9 209/757] libbpf: Fix unintentional success return code in bpf_object__load

From: Alex Gartrell <alexgartrell@...il.com>

[ 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@...il.com>
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Link: https://lore.kernel.org/bpf/20200826075549.1858580-1-alexgartrell@gmail.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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