From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753828AbeAIKFj (ORCPT + 1 other); Tue, 9 Jan 2018 05:05:39 -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 S1753645AbeAIKEh (ORCPT ); Tue, 9 Jan 2018 05:04:37 -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="9812814" 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 1/3] tracing: detect the string termination character when parsing user input string Date: Tue, 9 Jan 2018 17:55:46 +0800 Message-Id: <1515491748-25926-2-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 The usersapce can give a '\0' terminated C string or even has '\0' at the middle of input buffer. We need handle both these two cases correctly. Before this change, trace_get_user() will return a parsed string "\0" in below case. It is not expected (expects it skip all inputs) and cause the caller failed. open("/sys/kernel/debug/tracing//set_ftrace_pid", O_WRONLY|O_TRUNC) = 3 write(3, " \0", 2) = -1 EINVAL (Invalid argument) This patch try to make the parser '\0' aware to fix such issue. Since the caller expects trace_get_user() to parse whole input buffer, so this patch treat '\0' as a separator as whitespace. Signed-off-by: Changbin Du --- kernel/trace/trace.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 2a8d8a2..18526a1 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1194,9 +1194,14 @@ void trace_parser_put(struct trace_parser *parser) parser->buffer = NULL; } +static inline bool is_space_or_zero(char ch) +{ + return isspace(ch) || !ch; +} + /* - * trace_get_user - reads the user input string separated by space - * (matched by isspace(ch)) + * trace_get_user - reads the user input string separated by space or '\0' + * (matched by is_space_or_zero(ch)) * * For each string found the 'struct trace_parser' is updated, * and the function returns. @@ -1228,7 +1233,7 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf, */ if (!parser->cont) { /* skip white space */ - while (cnt && isspace(ch)) { + while (cnt && is_space_or_zero(ch)) { ret = get_user(ch, ubuf++); if (ret) goto out; @@ -1237,7 +1242,7 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf, } /* only spaces were written */ - if (isspace(ch)) { + if (is_space_or_zero(ch)) { *ppos += read; ret = read; goto out; @@ -1247,7 +1252,7 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf, } /* read the non-space input */ - while (cnt && !isspace(ch)) { + while (cnt && !is_space_or_zero(ch)) { if (parser->idx < parser->size - 1) parser->buffer[parser->idx++] = ch; else { @@ -1262,7 +1267,7 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf, } /* We either got finished input or we have to wait for another call. */ - if (isspace(ch)) { + if (is_space_or_zero(ch)) { parser->buffer[parser->idx] = 0; parser->cont = false; } else if (parser->idx < parser->size - 1) { -- 2.7.4