From nobody Mon Feb 9 17:22:00 2026 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.4]) by smtp.subspace.kernel.org (Postfix) with ESMTP id AFF6C257AC8; Mon, 14 Apr 2025 09:35:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.4 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744623344; cv=none; b=GupNzPKCINED4PVsCSljWM7uc4zGnVgK5gXEK7KPckgpF/0aEwqGJ+6a/cYq2n8y0ztxFqnEW43QHlcL8qnRGkxwZgFyaeVt2SzRR/2xFcRDNWhhC+cKjjevnLJASuRPNjONWjZMySUAUfEnh9QFDs//DkJyZDb9bkaRb+QPJEc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744623344; c=relaxed/simple; bh=qofaBpaVa18j32xfzQZLhDpGoO0stebsJoK1bv09/7Q=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=paFJ0Om27LJHOu6VBifSSTAWdqxAgv9HOwpLQYmxYzPvkcjp2TRpSIjnlZ25zfjUdrClGgLW92Kin+zT7JOfaflywWAHb6F9A9siB0omYS2zoS6w7CfFjbAbywWmW4vga4m8dqOVPA39oyIfV1SXOQK3aOGQC3D8gixQdm46Urg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=G2majBNR; arc=none smtp.client-ip=117.135.210.4 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="G2majBNR" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-Id:MIME-Version; bh=eExAn PO2f4LGlgR4ad3HevDpupPLJHXCFOUKXNGyZsI=; b=G2majBNRLIDFPgB2f2RQZ j3fOCvU80fzLKf+50eUgfDgQeEpKNLlDgWCMj6oNYNzL4+NyuIbNAZM5j/wAdbKr doDs+HoEFaGRDDzZ/dsy1OAsrnwSxNppkq/YyoXIg8ZO9a+4x1NXKBq2M+riHSAv FHDJiLTDwya8V/9kQss6lk= Received: from localhost.localdomain (unknown []) by gzga-smtp-mtada-g1-2 (Coremail) with SMTP id _____wDnj1Sb1vxnxkYWGg--.23370S3; Mon, 14 Apr 2025 17:34:22 +0800 (CST) From: Feng Yang To: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, hengqi.chen@gmail.com Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 bpf-next 1/3] libbpf: Fix event name too long error Date: Mon, 14 Apr 2025 17:34:00 +0800 Message-Id: <20250414093402.384872-2-yangfeng59949@163.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20250414093402.384872-1-yangfeng59949@163.com> References: <20250414093402.384872-1-yangfeng59949@163.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _____wDnj1Sb1vxnxkYWGg--.23370S3 X-Coremail-Antispam: 1Uf129KBjvJXoWxGFW7WryxZrWDZF47JFyfXrb_yoWrtr48pF 4DZrn0yF4ftay29FZ8Jrn5Z34F9r1kGFWUJr1DJr9xZF4xWF4UZa42kF4DCF15WrZ2vay3 Aa1jgry3Xa4xAFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jYlkxUUUUU= X-CM-SenderInfo: p1dqww5hqjkmqzuzqiywtou0bp/1tbiwhwveGf808xdSAAAsY Content-Type: text/plain; charset="utf-8" From: Feng Yang When the binary path is excessively long, the generated probe_name in libbpf exceeds the kernel's MAX_EVENT_NAME_LEN limit (64 bytes). This causes legacy uprobe event attachment to fail with error code -22. Before Fix: ./test_progs -t attach_probe/kprobe-long_name ...... libbpf: failed to add legacy kprobe event for 'bpf_kfunc_loooooooooooooooo= ooooooooooooooong_name+0x0': -EINVAL libbpf: prog 'handle_kprobe': failed to create kprobe 'bpf_kfunc_loooooooo= ooooooooooooooooooooooong_name+0x0' perf event: -EINVAL test_attach_kprobe_long_event_name:FAIL:attach_kprobe_long_event_name unex= pected error: -22 test_attach_probe:PASS:uprobe_ref_ctr_cleanup 0 nsec #13/11 attach_probe/kprobe-long_name:FAIL #13 attach_probe:FAIL ./test_progs -t attach_probe/uprobe-long_name ...... libbpf: failed to add legacy uprobe event for /root/linux-bpf/bpf-next/too= ls/testing/selftests/bpf/test_progs:0x13efd9: -EINVAL libbpf: prog 'handle_uprobe': failed to create uprobe '/root/linux-bpf/bpf= -next/tools/testing/selftests/bpf/test_progs:0x13efd9' perf event: -EINVAL test_attach_uprobe_long_event_name:FAIL:attach_uprobe_long_event_name unex= pected error: -22 #13/10 attach_probe/uprobe-long_name:FAIL #13 attach_probe:FAIL After Fix: ./test_progs -t attach_probe/uprobe-long_name #13/10 attach_probe/uprobe-long_name:OK #13 attach_probe:OK Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED ./test_progs -t attach_probe/kprobe-long_name #13/11 attach_probe/kprobe-long_name:OK #13 attach_probe:OK Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED Fixes: 46ed5fc33db9 ("libbpf: Refactor and simplify legacy kprobe code") Fixes: cc10623c6810 ("libbpf: Add legacy uprobe attaching support") Signed-off-by: Hengqi Chen Signed-off-by: Feng Yang --- tools/lib/bpf/libbpf.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index b2591f5cab65..9e047641e001 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -60,6 +60,8 @@ #define BPF_FS_MAGIC 0xcafe4a11 #endif =20 +#define MAX_EVENT_NAME_LEN 64 + #define BPF_FS_DEFAULT_PATH "/sys/fs/bpf" =20 #define BPF_INSN_SZ (sizeof(struct bpf_insn)) @@ -11142,10 +11144,10 @@ static void gen_kprobe_legacy_event_name(char *bu= f, size_t buf_sz, static int index =3D 0; int i; =20 - snprintf(buf, buf_sz, "libbpf_%u_%s_0x%zx_%d", getpid(), kfunc_name, offs= et, - __sync_fetch_and_add(&index, 1)); + snprintf(buf, buf_sz, "libbpf_%u_%d_%s_0x%zx", getpid(), + __sync_fetch_and_add(&index, 1), kfunc_name, offset); =20 - /* sanitize binary_path in the probe name */ + /* sanitize kfunc_name in the probe name */ for (i =3D 0; buf[i]; i++) { if (!isalnum(buf[i])) buf[i] =3D '_'; @@ -11270,7 +11272,7 @@ int probe_kern_syscall_wrapper(int token_fd) =20 return pfd >=3D 0 ? 1 : 0; } else { /* legacy mode */ - char probe_name[128]; + char probe_name[MAX_EVENT_NAME_LEN]; =20 gen_kprobe_legacy_event_name(probe_name, sizeof(probe_name), syscall_nam= e, 0); if (add_kprobe_event_legacy(probe_name, false, syscall_name, 0) < 0) @@ -11328,7 +11330,7 @@ bpf_program__attach_kprobe_opts(const struct bpf_pr= ogram *prog, func_name, offset, -1 /* pid */, 0 /* ref_ctr_off */); } else { - char probe_name[256]; + char probe_name[MAX_EVENT_NAME_LEN]; =20 gen_kprobe_legacy_event_name(probe_name, sizeof(probe_name), func_name, offset); @@ -11878,9 +11880,12 @@ static int attach_uprobe_multi(const struct bpf_pr= ogram *prog, long cookie, stru static void gen_uprobe_legacy_event_name(char *buf, size_t buf_sz, const char *binary_path, uint64_t offset) { + static int index =3D 0; int i; =20 - snprintf(buf, buf_sz, "libbpf_%u_%s_0x%zx", getpid(), binary_path, (size_= t)offset); + snprintf(buf, buf_sz, "libbpf_%u_%d_%s_0x%zx", getpid(), + __sync_fetch_and_add(&index, 1), + basename((void *)binary_path), (size_t)offset); =20 /* sanitize binary_path in the probe name */ for (i =3D 0; buf[i]; i++) { @@ -12312,7 +12317,7 @@ bpf_program__attach_uprobe_opts(const struct bpf_pr= ogram *prog, pid_t pid, pfd =3D perf_event_open_probe(true /* uprobe */, retprobe, binary_path, func_offset, pid, ref_ctr_off); } else { - char probe_name[PATH_MAX + 64]; + char probe_name[MAX_EVENT_NAME_LEN]; =20 if (ref_ctr_off) return libbpf_err_ptr(-EINVAL); --=20 2.43.0