From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by dpdk.org (Postfix) with ESMTP id D70332BD5; Fri, 8 Mar 2019 18:31:02 +0100 (CET) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 08 Mar 2019 09:31:01 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.58,456,1544515200"; d="scan'208";a="325477128" Received: from fyigit-mobl.ger.corp.intel.com (HELO [10.237.221.46]) ([10.237.221.46]) by fmsmga006.fm.intel.com with ESMTP; 08 Mar 2019 09:30:59 -0800 To: Bruce Richardson , Chaitanya Babu Talluri Cc: dev@dpdk.org, reshma.pattan@intel.com, jananeex.m.parthasarathy@intel.com, cristian.dumitrescu@intel.com, stable@dpdk.org References: <1550136631-32415-1-git-send-email-tallurix.chaitanya.babu@intel.com> <1552049150-5046-1-git-send-email-tallurix.chaitanya.babu@intel.com> <20190308140205.GA689548@bricha3-MOBL.ger.corp.intel.com> From: Ferruh Yigit Openpgp: preference=signencrypt Autocrypt: addr=ferruh.yigit@intel.com; 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WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.3 MIME-Version: 1.0 In-Reply-To: <20190308140205.GA689548@bricha3-MOBL.ger.corp.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [dpdk-dev] [PATCH v2] lib/cfgfile: replace strcat with strlcat X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 08 Mar 2019 17:31:03 -0000 On 3/8/2019 2:02 PM, Bruce Richardson wrote: > On Fri, Mar 08, 2019 at 12:45:50PM +0000, Chaitanya Babu Talluri wrote: >> Replace strcat with strlcat to avoid buffer overflow. >> >> Fixes: a6a47ac9c2 ("cfgfile: rework load function") >> Cc: stable@dpdk.org >> >> Signed-off-by: Chaitanya Babu Talluri >> --- >> v2: Instead of strcat, used strlcat. >> --- >> lib/librte_cfgfile/rte_cfgfile.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/lib/librte_cfgfile/rte_cfgfile.c b/lib/librte_cfgfile/rte_cfgfile.c >> index 7d8c941ea..3296bb6f8 100644 >> --- a/lib/librte_cfgfile/rte_cfgfile.c >> +++ b/lib/librte_cfgfile/rte_cfgfile.c >> @@ -8,6 +8,7 @@ >> #include >> #include >> #include >> +#include >> >> #include "rte_cfgfile.h" >> >> @@ -224,10 +225,11 @@ rte_cfgfile_load_with_params(const char *filename, int flags, >> _strip(split[1], strlen(split[1])); >> char *end = memchr(split[1], '\\', strlen(split[1])); >> >> + size_t split_len = strlen(split[1]) + 1; >> while (end != NULL) { >> if (*(end+1) == params->comment_character) { >> *end = '\0'; >> - strcat(split[1], end+1); >> + strlcat(split[1], end+1, split_len); > > I don't think this will do what you want. Remember that strlcat takes the > total length of the buffer, which means that if split_len is set to the > current length (as you do before the while statement), then passing that > as the length parameter will cause strlcat to do nothing, since it sees the > buffer as already full. The logic doesn't lengthen the 'split[1]' content, indeed it reduces the initial size although it uses string concatenation, that is why it should be OK to use 'split_len' here. What code does is, it finds specific char in 'split' buffer and removes it by shifting remaining chars one byte to the left. So it shouldn't pass the initial size of the buffer. There is a overlapping strings concern, which 'strcat' & 'strlcat' don't support, but I guess it is OK here since we are sure that strings are separated by a NULL, so where a char read and written should be different although overall dst and src buffers overlap.