Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753724AbeAIKEt (ORCPT + 1 other); Tue, 9 Jan 2018 05:04:49 -0500 Received: from mga01.intel.com ([192.55.52.88]:22519 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753702AbeAIKEp (ORCPT ); Tue, 9 Jan 2018 05:04:45 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,335,1511856000"; d="scan'208";a="9812862" From: changbin.du@intel.com To: rostedt@goodmis.org Cc: jolsa@redhat.com, peterz@infradead.org, mingo@redhat.com, alexander.shishkin@linux.intel.com, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Changbin Du Subject: [PATCH 3/3] tracing: don't set parser->cont if it has reached the end of input buffer Date: Tue, 9 Jan 2018 17:55:48 +0800 Message-Id: <1515491748-25926-4-git-send-email-changbin.du@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1515491748-25926-1-git-send-email-changbin.du@intel.com> References: <1515491748-25926-1-git-send-email-changbin.du@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Changbin Du We should not set parser->cont if it has reached the end of input buffer. And since some callers (like ftrace_graph_write()) treat it as an error condition if trace_parser_cont() returns true. For example, if userspace set 'set_ftrace_filter' by writing: write(3, "abcdefg", 7) Then in the kernel function ftrace_regex_write(), ftrace_process_regex() will not be executed. The result is that the given filter will not be applied at all. ftrace_regex_write() { ... read = trace_get_user(parser, ubuf, cnt, ppos); if (read >= 0 && trace_parser_loaded(parser) && !trace_parser_cont(parser)) { ret = ftrace_process_regex(iter, parser->buffer, parser->idx, enable); ... } ... } Signed-off-by: Changbin Du --- kernel/trace/trace.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index e1baca0..79fdce2 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1269,7 +1269,8 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf, parser->buffer[parser->idx] = 0; parser->cont = false; } else if (parser->idx < parser->size - 2) { - parser->cont = true; + parser->cont = !!cnt; + parser->buffer[parser->idx++] = ch; /* Make sure the parsed string always terminates with '\0'. */ parser->buffer[parser->idx] = 0; -- 2.7.4