From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=192.55.52.88; helo=mga01.intel.com; envelope-from=ruiyu.ni@intel.com; receiver=edk2-devel@lists.01.org Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id F01CC21E48F2F for ; Tue, 23 Jan 2018 19:30:30 -0800 (PST) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 23 Jan 2018 19:35:58 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,405,1511856000"; d="scan'208";a="24943520" Received: from ray-dev.ccr.corp.intel.com (HELO [10.239.9.19]) ([10.239.9.19]) by fmsmga001.fm.intel.com with ESMTP; 23 Jan 2018 19:35:57 -0800 To: Jian J Wang , edk2-devel@lists.01.org References: <20180123021441.4784-1-jian.j.wang@intel.com> From: "Ni, Ruiyu" Message-ID: <8e457c40-fb85-5e9d-9dba-e3eff18cba4e@Intel.com> Date: Wed, 24 Jan 2018 11:35:36 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: <20180123021441.4784-1-jian.j.wang@intel.com> Subject: Re: [PATCH] ShellPkg/UefiShellLevel3CommandsLib: fix string over-read X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 24 Jan 2018 03:30:31 -0000 Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit On 1/23/2018 10:14 AM, Jian J Wang wrote: > In the for-loop condition of original code, the expression > > *CurrentCommand != CHAR_NULL > > is put before expression > > CurrentCommand < SortedCommandList + SortedCommandListSize/sizeof(CHAR16) > > When CurrentCommand walks to the end of string buffer, one more character > over the end of string buffer will be read and then stop. > > To fix this issue, just move the last expression to the first one. Because > of short-circuit evaludation of and-expression, the following one > > *CurrentCommand != CHAR_NULL > > will not be evaluated if the expression before it is evaludated as FALSE. > > Cc: Ruiyu Ni > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Jian J Wang > --- > ShellPkg/Library/UefiShellLevel3CommandsLib/Help.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/ShellPkg/Library/UefiShellLevel3CommandsLib/Help.c b/ShellPkg/Library/UefiShellLevel3CommandsLib/Help.c > index a71ade3a20..75e3d74200 100644 > --- a/ShellPkg/Library/UefiShellLevel3CommandsLib/Help.c > +++ b/ShellPkg/Library/UefiShellLevel3CommandsLib/Help.c > @@ -397,7 +397,7 @@ ShellCommandRunHelp ( > CopyListOfCommandNamesWithDynamic(&SortedCommandList, &SortedCommandListSize); > > for (CurrentCommand = SortedCommandList > - ; CurrentCommand != NULL && *CurrentCommand != CHAR_NULL && CurrentCommand < SortedCommandList + SortedCommandListSize/sizeof(CHAR16) > + ; CurrentCommand < SortedCommandList + SortedCommandListSize/sizeof(CHAR16) && CurrentCommand != NULL && *CurrentCommand != CHAR_NULL > ; CurrentCommand += StrLen(CurrentCommand) + 1 > ) { > // > How about keep "CurrentCommand != NULL" in the beginning? I agree to swap the other two checks. -- Thanks, Ray