From 3d79bc7e88a22371df575bb61fa2e18c61e08c58 Mon Sep 17 00:00:00 2001

From: Quentin Monnet <quentin@isovalent.com>

Date: Thu, 29 Jul 2021 17:20:21 +0100

Subject: [PATCH] libbpf: Return non-null error on failures in libbpf_find_prog_btf_id()

Git-commit: 6d2d73cdd673d493f9f3751188757129b1d23fb7

Patch-mainline: v5.15-rc1

References: stable-5.14.4

[ 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@isovalent.com>

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

Link: https://lore.kernel.org/bpf/20210729162028.29512-2-quentin@isovalent.com

Signed-off-by: Sasha Levin <sashal@kernel.org>

Acked-by: Takashi Iwai <tiwai@suse.de>

---

 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");

-- 

2.26.2