From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpbgau2.qq.com (smtpbgau2.qq.com [54.206.34.216]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9BD42175A6E; Tue, 14 Apr 2026 01:40:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=54.206.34.216 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776130862; cv=none; b=ZbiF+fPirP6Sk5xnsyzbKCI3qOciXnytazqu9XTK7+asSzzd8LgIJ/xiq1IVgQ1NDYt99+AEVbt63XZ+VGRLtmm6gypTTVi0LyXuPWc3rNtBLW+a5DUPo56TdS4MYGspLODuVj5r/2XKmYqoHdw/vGHdsXU7wQjtFXJkTTam//8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776130862; c=relaxed/simple; bh=CVUH62THuE+t3vMuudrdn17dofVDtLU4tnG9KdHkRa4=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version:Content-Type; b=i6vP2g2aNTV0uLUJc7Q1ngQaUh6DbdarQIUlK2UtYOVoz3ZL2v+ONnem+PSo+/KLPrKfkDJisw2ez2Ll7Rk5g9vTFciZVXoxZfAYgt6UCMYFs2XYaXWC2XdgO2T6Xpe0/rmrX2szgoQI79p9yhXLP5sHQ0po5tzzifCDXOFZPhs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=uniontech.com; spf=pass smtp.mailfrom=uniontech.com; dkim=pass (1024-bit key) header.d=uniontech.com header.i=@uniontech.com header.b=HndldtIv; arc=none smtp.client-ip=54.206.34.216 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=uniontech.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=uniontech.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=uniontech.com header.i=@uniontech.com header.b="HndldtIv" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=uniontech.com; s=onoh2408; t=1776130826; bh=2o2nXaGn3xy5dIW84oGoCrtG+4Y7V7BBZuKTJB3Mq+A=; h=From:To:Subject:Date:Message-Id:MIME-Version; b=HndldtIvXmRS8Wd/66Kx/pGm0VHAZGhsOsCBGWJnCi9Yqnf0cKz0XHrTnNF6/4sty 4RjQ4RwlM8w1HallqIqdxkzC4SohJG9hvg46NBweo3fXrcNa7VAvU8ooFT+Zvk6wWK Lfjgz5pyHa21QuJo7T171IDrpC6AtGxKBdsxHqE8= X-QQ-mid: zesmtpip2t1776130810t54227dfc X-QQ-Originating-IP: PDvphrMKRxJXOzB0Ljt/SoSN7n9Nsoceku01euB8pcQ= Received: from localhost.localdomain ( [localhost]) by bizesmtp.qq.com (ESMTP) with id ; Tue, 14 Apr 2026 09:40:03 +0800 (CST) X-QQ-SSF: 0000000000000000000000000000000 X-QQ-GoodBg: 1 X-BIZMAIL-ID: 6462308600708098347 EX-QQ-RecipientCnt: 9 From: Yihan Ding To: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, bpf@vger.kernel.org Cc: shuah@kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@uniontech.com, Yihan Ding Subject: [PATCH bpf] bpf: allow UTF-8 literals in bpf_bprintf_prepare() Date: Tue, 14 Apr 2026 09:40:01 +0800 Message-Id: <20260414014001.814324-1-dingyihan@uniontech.com> X-Mailer: git-send-email 2.20.1 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-QQ-SENDSIZE: 520 Feedback-ID: zesmtpip:uniontech.com:qybglogicsvrsz:qybglogicsvrsz4b-0 X-QQ-XMAILINFO: OUC5DGN0mB58SbT23Ysuy1huG8Skch3ykYU0WJWEsu+9hn3TzU1tu2go f/HXpU7xy/RkNfsq9X8ypD32qVtNd4y62qVSFSR/TCtPSwTnTwNdtl9zez4nVsrIial04KK lvSIp4yqH631lYGZCMeq2b/lkTs1C9uKHZGy/BCXnSr23EP2W7mr+EMsXmpVIvKxjFvmAt0 PW9XPpF6Pf0JIIulvVr2Yy42ovRIEAYad3CWUvRxkRr7TRfG00wbU7IjcnID69rRvo7vKzG PETMaNbXtqDyUPcxg3wEP4XLuI9BKjlMWOfFKgyfqvrVLOF6VgpgKQlnrvuNLiznZpBEIh0 uxw0xEB7xY589i5FkAjh5t2CVVzOIBnce+lXdOd9YiAcwcqc9Dsi644ttIR4cEzQ4SR3xsf kbulxK84fbrRu0N4MOjVLy3tcUIPz29UiIhZmTWo+ddxg0BOMQQ+ILtEtCwIVDyeTD7TTf3 brWOnSfEnp6I161to06rIKSzvey/MUM69ipYRhB9ESReIS0Y6s2JBIqXIjd7dmSyBctMncG 7VG9MYbIbkT3uhZkh4A51xNVP2ZshVZi90ClN44pGPxFwUuhK34VodBcyuLKQEMciRPzQ3V igAGFEITpbclKavysupXWSPVR/QgQTJrACMr0AK7l7VAN3tSiUO9hcuMJ6mBePN1vRlx0GW QdfVGZJfHT8YxThvBoa97OcO55Sl6c3iROrZIcE+BdGYLc22fR9dHGlhvuEswjfs5BOF1GV DO9W5NW/1SkgclGFO15vKwdmIM/w7QzLmypBpQWURZDqllZqfSf2P3mm6uabYMx/Z8488Fp WTX1ZQ+OxZEOnY2Q86DuVU+DkLsYm55HQKeD+VWpLqUTmPgp2ZCwl4NucL8FVo/ONHyyRpv 8WkzNmznLCzH8c2aJK2ypkg7JoaWVXHF+3V11qRUzSCVf+hzOP9PenXQZZ4C+RmCjEfmIjX TVSvDZPaH+6dTUTD5LnJ3nBHkqrCULt1zQKRhgydAsqAH5VSgfPE8n21sU5FGLs7iLK6gWL 7zHVgBvQ== X-QQ-XMRINFO: Nq+8W0+stu50tPAe92KXseR0ZZmBTk3gLg== X-QQ-RECHKSPAM: 0 bpf_bprintf_prepare() currently rejects any non-ASCII byte in the format string, such as UTF-8 Chinese text. All BPF formatted output helpers that go through bpf_bprintf_prepare(), such as bpf_trace_printk(), bpf_seq_printf() and bpf_snprintf(), only need ASCII parsing for conversion specifiers. Plain text does not need that restriction, but today any byte >= 0x80 makes the format fail validation. As a result, UTF-8 text literals are rejected even when they are not part of a format specifier. In practice, an ASCII-only bpf_trace_printk() format works, while the same format with UTF-8 literal text produces no trace output. Allow non-ASCII bytes in plain text while keeping the existing control character checks and keeping format specifiers ASCII-only. This preserves the current parsing rules for '%' sequences and allows valid UTF-8 text to be emitted. Extend the trace_printk selftest accordingly by emitting both ASCII and UTF-8 strings and verifying that both appear in the trace output. Fixes: 48cac3f4a96d ("bpf: Implement formatted output helpers with bstr_printf") Signed-off-by: Yihan Ding --- Testing: - Reproduced on x86_64 without this patch: ASCII trace output works, while UTF-8 literal text in bpf_trace_printk() is rejected and produces no trace output. - Verified with tools/testing/selftests/bpf: ./test_progs -t trace_printk kernel/bpf/helpers.c | 21 +++++++++++++----- .../selftests/bpf/prog_tests/trace_printk.c | 22 ++++++++++++++----- .../selftests/bpf/progs/trace_printk.c | 5 +++++ 3 files changed, 38 insertions(+), 10 deletions(-) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 6eb6c82ed2ee..e2f103297e4a 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -845,7 +845,13 @@ int bpf_bprintf_prepare(const char *fmt, u32 fmt_size, const u64 *raw_args, data->buf = buffers->buf; for (i = 0; i < fmt_size; i++) { - if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i])) { + unsigned char c = fmt[i]; + + /* + * Permit non-ASCII bytes in plain text so UTF-8 messages can be + * emitted, while keeping format specifiers ASCII-only. + */ + if (isascii(c) && !isprint(c) && !isspace(c)) { err = -EINVAL; goto out; } @@ -867,6 +873,10 @@ int bpf_bprintf_prepare(const char *fmt, u32 fmt_size, const u64 *raw_args, * always access fmt[i + 1], in the worst case it will be a 0 */ i++; + if (!isascii((unsigned char)fmt[i])) { + err = -EINVAL; + goto out; + } /* skip optional "[0 +-][num]" width formatting field */ while (fmt[i] == '0' || fmt[i] == '+' || fmt[i] == '-' || @@ -881,8 +891,9 @@ int bpf_bprintf_prepare(const char *fmt, u32 fmt_size, const u64 *raw_args, if (fmt[i] == 'p') { sizeof_cur_arg = sizeof(long); - if (fmt[i + 1] == 0 || isspace(fmt[i + 1]) || - ispunct(fmt[i + 1])) { + if (fmt[i + 1] == 0 || + isspace((unsigned char)fmt[i + 1]) || + ispunct((unsigned char)fmt[i + 1])) { if (tmp_buf) cur_arg = raw_args[num_spec]; goto nocopy_fmt; @@ -958,8 +969,8 @@ int bpf_bprintf_prepare(const char *fmt, u32 fmt_size, const u64 *raw_args, fmt_ptype = fmt[i]; fmt_str: if (fmt[i + 1] != 0 && - !isspace(fmt[i + 1]) && - !ispunct(fmt[i + 1])) { + !isspace((unsigned char)fmt[i + 1]) && + !ispunct((unsigned char)fmt[i + 1])) { err = -EINVAL; goto out; } diff --git a/tools/testing/selftests/bpf/prog_tests/trace_printk.c b/tools/testing/selftests/bpf/prog_tests/trace_printk.c index e56e88596d64..f7b03dc4eaf4 100644 --- a/tools/testing/selftests/bpf/prog_tests/trace_printk.c +++ b/tools/testing/selftests/bpf/prog_tests/trace_printk.c @@ -6,18 +6,21 @@ #include "trace_printk.lskel.h" #define SEARCHMSG "testing,testing" +#define SEARCHMSG_UTF8 "中文,测试" static void trace_pipe_cb(const char *str, void *data) { if (strstr(str, SEARCHMSG) != NULL) - (*(int *)data)++; + ((int *)data)[0]++; + if (strstr(str, SEARCHMSG_UTF8) != NULL) + ((int *)data)[1]++; } void serial_test_trace_printk(void) { struct trace_printk_lskel__bss *bss; struct trace_printk_lskel *skel; - int err = 0, found = 0; + int err = 0, found[2] = {}; skel = trace_printk_lskel__open(); if (!ASSERT_OK_PTR(skel, "trace_printk__open")) @@ -46,11 +49,20 @@ void serial_test_trace_printk(void) if (!ASSERT_GT(bss->trace_printk_ret, 0, "bss->trace_printk_ret")) goto cleanup; - /* verify our search string is in the trace buffer */ - ASSERT_OK(read_trace_pipe_iter(trace_pipe_cb, &found, 1000), + if (!ASSERT_GT(bss->trace_printk_utf8_ran, 0, "bss->trace_printk_utf8_ran")) + goto cleanup; + + if (!ASSERT_GT(bss->trace_printk_utf8_ret, 0, "bss->trace_printk_utf8_ret")) + goto cleanup; + + /* verify our search strings are in the trace buffer */ + ASSERT_OK(read_trace_pipe_iter(trace_pipe_cb, found, 1000), "read_trace_pipe_iter"); - if (!ASSERT_EQ(found, bss->trace_printk_ran, "found")) + if (!ASSERT_EQ(found[0], bss->trace_printk_ran, "found")) + goto cleanup; + + if (!ASSERT_EQ(found[1], bss->trace_printk_utf8_ran, "found_utf8")) goto cleanup; cleanup: diff --git a/tools/testing/selftests/bpf/progs/trace_printk.c b/tools/testing/selftests/bpf/progs/trace_printk.c index 6695478c2b25..97afe8b149b0 100644 --- a/tools/testing/selftests/bpf/progs/trace_printk.c +++ b/tools/testing/selftests/bpf/progs/trace_printk.c @@ -10,13 +10,18 @@ char _license[] SEC("license") = "GPL"; int trace_printk_ret = 0; int trace_printk_ran = 0; +int trace_printk_utf8_ret = 0; +int trace_printk_utf8_ran = 0; -const char fmt[] = "Testing,testing %d\n"; +static const char fmt[] = "Testing,testing %d\n"; +static const char utf8_fmt[] = "中文,测试 %d\n"; SEC("fentry/" SYS_PREFIX "sys_nanosleep") int sys_enter(void *ctx) { trace_printk_ret = bpf_trace_printk(fmt, sizeof(fmt), ++trace_printk_ran); + trace_printk_utf8_ret = bpf_trace_printk(utf8_fmt, sizeof(utf8_fmt), + ++trace_printk_utf8_ran); return 0; } -- 2.20.1