From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752002AbdBJNXr (ORCPT ); Fri, 10 Feb 2017 08:23:47 -0500 Received: from mail.kernel.org ([198.145.29.136]:40584 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751066AbdBJNXo (ORCPT ); Fri, 10 Feb 2017 08:23:44 -0500 From: Masami Hiramatsu To: Ingo Molnar , Steven Rostedt Cc: Masami Hiramatsu , linux-kernel@vger.kernel.org, Peter Zijlstra , Ananth N Mavinakayanahalli , Thomas Gleixner , "H . Peter Anvin" , Namhyung Kim , Andrew Morton Subject: [PATCH V2 1/2] tracing/probes: Fix a warning message to show correct maximum length Date: Fri, 10 Feb 2017 22:21:55 +0900 Message-Id: <148673290462.2579.7966778294009665632.stgit@devbox> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20170210075302.GB24405@gmail.com> References: <20170210075302.GB24405@gmail.com> In-Reply-To: <20170210075302.GB24405@gmail.com> References: <20170210075302.GB24405@gmail.com> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since tracing/*probe_events will accept a probe definition up to 4096 - 2 ('\n' and '\0') bytes, it must show 4094 instead of 4096 in warning message. Note that there is one possible case of exceed 4094. If user prepare 4096 bytes null-terminated string and syscall write it with the count == 4095, then it can be accepted. However, if user puts a '\n' after that, it must rejected. So IMHO, the warning message should indicate shorter one, since it is safer. Signed-off-by: Masami Hiramatsu --- kernel/trace/trace_probe.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index 2a06f1f..847c1e0 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -678,8 +678,9 @@ ssize_t traceprobe_probes_write(struct file *file, const char __user *buffer, if (done + size < count) { if (buf != kbuf) break; + /* This can accept WRITE_BUFSIZE - 2 ('\n' + '\0') */ pr_warn("Line length is too long: Should be less than %d\n", - WRITE_BUFSIZE); + WRITE_BUFSIZE - 2); ret = -EINVAL; goto out; }