From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1039688AbdDUNLz (ORCPT ); Fri, 21 Apr 2017 09:11:55 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:47211 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1039560AbdDUNLv (ORCPT ); Fri, 21 Apr 2017 09:11:51 -0400 Reply-To: pc@us.ibm.com Subject: Re: [PATCH v4 3/7] kprobes: validate the symbol name provided during probe registration References: <6e14d22994530fb5200c74d1593e73541d3b8028.1492604782.git.naveen.n.rao@linux.vnet.ibm.com> <20170421123234.6895-1-naveen.n.rao@linux.vnet.ibm.com> To: "Naveen N. Rao" , Michael Ellerman , Masami Hiramatsu Cc: linuxppc-dev@lists.ozlabs.org, Ingo Molnar , linux-kernel@vger.kernel.org From: Paul Clarke Date: Fri, 21 Apr 2017 08:11:40 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170421123234.6895-1-naveen.n.rao@linux.vnet.ibm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 17042113-0012-0000-0000-000014181094 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006948; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000208; SDB=6.00850476; UDB=6.00420114; IPR=6.00629196; BA=6.00005305; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015125; XFM=3.00000013; UTC=2017-04-21 13:11:49 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17042113-0013-0000-0000-00004D2E7408 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-04-21_09:,, 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-1704210243 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. > + return false; > + s++; > + } else > + s = name; > + > + sym_len = strnlen(s, KSYM_NAME_LEN); > + if (sym_len <= 0 || sym_len >= KSYM_NAME_LEN) here, too. > + return false; > + > + return true; > +} PC