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From: Rafael David Tinoco <rafaeldtinoco@gmail.com>
To: Rafael David Tinoco <rafaeldtinoco@gmail.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>,
	bpf@vger.kernel.org, sunyucong@gmail.com,
	alexei.starovoitov@gmail.com
Subject: Re: [PATCH bpf-next v2] libbpf: fix build error introduced by legacy kprobe feature
Date: Tue, 14 Sep 2021 18:39:07 -0300	[thread overview]
Message-ID: <4B1531CC-63FE-4D22-8645-9EDB666F2707@gmail.com> (raw)
In-Reply-To: <20210914213554.2338381-1-rafaeldtinoco@gmail.com>


> -	char cmd[192], probename[128], probefunc[128];
> +	char cmd[288] = "\0", probename[128] = "\0", probefunc[128] = "\0";
> 	const char *file = "/sys/kernel/debug/tracing/kprobe_events";

I had gcc-10 with:

libbpf.c: In function ‘poke_kprobe_events’:
libbpf.c:9012:37: error: ‘%s’ directive output may be truncated writing up to 127 bytes into a region of size between 62 and 189 [-Werror=format-truncation=]
 9012 |   snprintf(cmd, sizeof(cmd), "%c:%s %s",
      |                                     ^~
In file included from /usr/include/stdio.h:866,
                 from libbpf.c:17:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:71:10: note: ‘__builtin___snprintf_chk’ output between 4 and 258 bytes into a destination of size 192
   71 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   72 |        __glibc_objsize (__s), __fmt,
      |        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   73 |        __va_arg_pack ());
      |        ~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

locally AND it fixed the issue for me but Alexei reported:

https://github.com/kernel-patches/bpf/runs/3603448190

with a truncation of max 258 bytes. I raised cmd size to 288. 

Let's see if that fixes the issue.


  reply	other threads:[~2021-09-14 21:39 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-30  5:33 [PATCH v3 bpf-next 00/14] BPF perf link and user-provided bpf_cookie Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 01/14] bpf: refactor BPF_PROG_RUN into a function Andrii Nakryiko
2021-07-30 17:19   ` Yonghong Song
2021-08-09 22:43   ` Daniel Borkmann
2021-08-10  0:28     ` Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 02/14] bpf: refactor BPF_PROG_RUN_ARRAY family of macros into functions Andrii Nakryiko
2021-08-09 23:00   ` Daniel Borkmann
2021-08-10  0:36     ` Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 03/14] bpf: refactor perf_event_set_bpf_prog() to use struct bpf_prog input Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 04/14] bpf: implement minimal BPF perf link Andrii Nakryiko
2021-07-30 17:24   ` Yonghong Song
2021-07-30  5:34 ` [PATCH v3 bpf-next 05/14] bpf: allow to specify user-provided bpf_cookie for BPF perf links Andrii Nakryiko
2021-07-30 22:02   ` Yonghong Song
2021-08-09 23:30   ` Daniel Borkmann
2021-08-10  0:52     ` Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 06/14] bpf: add bpf_get_attach_cookie() BPF helper to access bpf_cookie value Andrii Nakryiko
2021-07-30 22:13   ` Yonghong Song
2021-07-30  5:34 ` [PATCH v3 bpf-next 07/14] libbpf: re-build libbpf.so when libbpf.map changes Andrii Nakryiko
2021-07-30 22:31   ` Yonghong Song
2021-07-30  5:34 ` [PATCH v3 bpf-next 08/14] libbpf: remove unused bpf_link's destroy operation, but add dealloc Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 09/14] libbpf: use BPF perf link when supported by kernel Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 10/14] libbpf: add bpf_cookie support to bpf_link_create() API Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 11/14] libbpf: add bpf_cookie to perf_event, kprobe, uprobe, and tp attach APIs Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 12/14] selftests/bpf: test low-level perf BPF link API Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 13/14] selftests/bpf: extract uprobe-related helpers into trace_helpers.{c,h} Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 14/14] selftests/bpf: add bpf_cookie selftests for high-level APIs Andrii Nakryiko
2021-08-01  5:11 ` [PATCH bpf-next v4] libbpf: introduce legacy kprobe events support Rafael David Tinoco
2021-08-06 22:29   ` Andrii Nakryiko
2021-09-12  6:48     ` [PATCH bpf-next v5] " Rafael David Tinoco
2021-09-12  6:52       ` Rafael David Tinoco
2021-09-14  4:44       ` Andrii Nakryiko
2021-09-14  5:02         ` Rafael David Tinoco
2021-09-14  5:21           ` Andrii Nakryiko
2021-09-14 14:27             ` sunyucong
2021-09-14 15:42               ` Rafael David Tinoco
2021-09-14 20:34                 ` [PATCH bpf-next] libbpf: fix build error introduced by legacy kprobe feature Rafael David Tinoco
2021-09-14 21:04                   ` Alexei Starovoitov
2021-09-14 21:35                 ` [PATCH bpf-next v2] " Rafael David Tinoco
2021-09-14 21:39                   ` Rafael David Tinoco [this message]
2021-09-14 21:48                     ` Andrii Nakryiko

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