From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1039910AbdDUN0E convert rfc822-to-8bit (ORCPT ); Fri, 21 Apr 2017 09:26:04 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:55652 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1039853AbdDUN0C (ORCPT ); Fri, 21 Apr 2017 09:26:02 -0400 Date: Fri, 21 Apr 2017 13:25:00 +0000 From: "Naveen N. Rao" Subject: Re: [PATCH v4 3/7] kprobes: validate the symbol name provided during probe registration To: Masami Hiramatsu , Michael Ellerman , pc@us.ibm.com Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Ingo Molnar References: <6e14d22994530fb5200c74d1593e73541d3b8028.1492604782.git.naveen.n.rao@linux.vnet.ibm.com> <20170421123234.6895-1-naveen.n.rao@linux.vnet.ibm.com> In-Reply-To: User-Agent: astroid/0.8 (https://github.com/astroidmail/astroid) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8BIT X-TM-AS-MML: disable x-cbid: 17042113-0040-0000-0000-0000030A7D22 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17042113-0041-0000-0000-00000C829F56 Message-Id: <1492781012.pcpyah5v9j.astroid@naverao1-tp.none> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-04-21_10:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1704210245 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Excerpts from Paul Clarke's message of April 21, 2017 18:41: > a nit or two, below... > > On 04/21/2017 07:32 AM, Naveen N. Rao wrote: >> diff --git a/kernel/kprobes.c b/kernel/kprobes.c >> index 6a128f3a7ed1..ff9b1ac72a38 100644 >> --- a/kernel/kprobes.c >> +++ b/kernel/kprobes.c >> @@ -1383,6 +1383,34 @@ bool within_kprobe_blacklist(unsigned long addr) >> } >> >> /* >> + * We mainly want to ensure that the provided string is of a reasonable length >> + * and is of the form [:], so that this is safe to process >> + * further. >> + * We don't worry about invalid characters as those will just prevent >> + * matching existing kallsyms. >> + */ >> +bool is_valid_kprobe_symbol_name(const char *name) >> +{ >> + size_t sym_len; >> + const char *s; >> + >> + s = strnchr(name, ':', MODULE_NAME_LEN + KSYM_NAME_LEN + 1); >> + if (s) { >> + sym_len = (size_t)(s - name); >> + if (sym_len <= 0 || sym_len >= MODULE_NAME_LEN) > > "sym_len <= 0" looks odd here, since sym_len is likely unsigned and would never be less than zero, anyway. Ugh.. habits :/ I'll wait for Masami/Michael's feedback before re-spinning. Thanks for the review, - Naveen