[PATCH 5.14 143/334] libbpf: Return non-null error on failures in libbpf_find_prog_btf_id()

[Greg Kroah-Hartman]

From: Quentin Monnet <quentin@xxxxxxxxxxxxx>

[ Upstream commit 6d2d73cdd673d493f9f3751188757129b1d23fb7 ]

Variable "err" is initialised to -EINVAL so that this error code is
returned when something goes wrong in libbpf_find_prog_btf_id().
However, a recent change in the function made use of the variable in
such a way that it is set to 0 if retrieving linear information on the
program is successful, and this 0 value remains if we error out on
failures at later stages.

Let's fix this by setting err to -EINVAL later in the function.

Fixes: e9fc3ce99b34 ("libbpf: Streamline error reporting for high-level APIs")
Signed-off-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20210729162028.29512-2-quentin@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 tools/lib/bpf/libbpf.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index aa5ad6fc5f40..2234d5c33177 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -9515,7 +9515,7 @@ static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd)
 	struct bpf_prog_info_linear *info_linear;
 	struct bpf_prog_info *info;
 	struct btf *btf = NULL;
-	int err = -EINVAL;
+	int err;
 
 	info_linear = bpf_program__get_prog_info_linear(attach_prog_fd, 0);
 	err = libbpf_get_error(info_linear);
@@ -9524,6 +9524,8 @@ static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd)
 			attach_prog_fd);
 		return err;
 	}
+
+	err = -EINVAL;
 	info = &info_linear->info;
 	if (!info->btf_id) {
 		pr_warn("The target program doesn't have BTF\n");
-- 
2.30.2