linux-kernel - Re: [PATCH v2 bpf-next] libbpf: Improve debug message when the base BTF cannot be found

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Zz_YBK3SWnZnze-n@bolson-desk>
Date: Thu, 21 Nov 2024 19:01:56 -0600
From: "Olson, Matthew" <matthew.olson@...el.com>
To: Andrii Nakryiko <andrii@...nel.org>, Eduard Zingerman <eddyz87@...il.com>,
	<bpf@...r.kernel.org>
CC: Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann
	<daniel@...earbox.net>, Martin KaFai Lau <martin.lau@...ux.dev>, Song Liu
	<song@...nel.org>, Yonghong Song <yonghong.song@...ux.dev>, John Fastabend
	<john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>, Stanislav Fomichev
	<sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 bpf-next] libbpf: Improve debug message when the base
 BTF cannot be found

>From 22ed11ee2153fc921987eac7de24f564da9f9230 Mon Sep 17 00:00:00 2001
From: Ben Olson <matthew.olson@...el.com>
Date: Thu, 21 Nov 2024 11:26:35 -0600
Subject: [PATCH v2 bpf-next] libbpf: Improve debug message when the base BTF
 cannot be found

When running `bpftool` on a kernel module installed in `/lib/modules...`,
this error is encountered if the user does not specify `--base-btf` to
point to a valid base BTF (e.g. usually in `/sys/kernel/btf/vmlinux`).
However, looking at the debug output to determine the cause of the error
simply says `Invalid BTF string section`, which does not point to the
actual source of the error. This just improves that debug message to tell
users what happened.

Signed-off-by: Ben Olson <matthew.olson@...el.com>
---

Changed in v2:
  * Made error message better reflect the condition

 tools/lib/bpf/btf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 12468ae0d573..a4ae2df68b91 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -283,7 +283,7 @@ static int btf_parse_str_sec(struct btf *btf)
     return -EINVAL;
   }
   if (!btf->base_btf && start[0]) {
-    pr_debug("Invalid BTF string section\n");
+    pr_debug("Malformed BTF string section, did you forget to provide base BTF?\n");
     return -EINVAL;
   }
   return 0;
--
2.47.0