From nobody Mon Feb 9 08:56:23 2026 Delivered-To: importer@patchew.org Received-SPF: none (zoho.com: 198.145.21.10 is neither permitted nor denied by domain of lists.01.org) client-ip=198.145.21.10; envelope-from=edk2-devel-bounces@lists.01.org; helo=ml01.01.org; Authentication-Results: mx.zoho.com; spf=none (zoho.com: 198.145.21.10 is neither permitted nor denied by domain of lists.01.org) smtp.mailfrom=edk2-devel-bounces@lists.01.org; Return-Path: Received: from ml01.01.org (ml01.01.org [198.145.21.10]) by mx.zohomail.com with SMTPS id 1496211212165121.18951192350801; Tue, 30 May 2017 23:13:32 -0700 (PDT) Received: from [127.0.0.1] (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 89D8D21AEBADF; Tue, 30 May 2017 23:12:30 -0700 (PDT) Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) (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 2223921AE3CD9 for ; Tue, 30 May 2017 23:12:27 -0700 (PDT) Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 30 May 2017 23:13:27 -0700 Received: from shwdeopenpsi014.ccr.corp.intel.com ([10.239.9.13]) by fmsmga005.fm.intel.com with ESMTP; 30 May 2017 23:13:25 -0700 X-Original-To: edk2-devel@lists.01.org X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.38,422,1491289200"; d="scan'208";a="108548396" From: Hao Wu To: edk2-devel@lists.01.org Date: Wed, 31 May 2017 14:13:18 +0800 Message-Id: <20170531061319.21976-2-hao.a.wu@intel.com> X-Mailer: git-send-email 2.12.0.windows.1 In-Reply-To: <20170531061319.21976-1-hao.a.wu@intel.com> References: <20170531061319.21976-1-hao.a.wu@intel.com> Subject: [edk2] [PATCH v2 1/2] MdePkg/BasePrintLib: Avoid reading content beyond the format string X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Hao Wu , Michael Kinney , Jiewen Yao , Liming Gao MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Errors-To: edk2-devel-bounces@lists.01.org Sender: "edk2-devel" X-ZohoMail: RSF_4 Z_629925259 SPT_0 Content-Type: text/plain; charset="utf-8" https://bugzilla.tianocore.org/show_bug.cgi?id=3D567 In function BasePrintLibSPrintMarker(), when processing ASCII format strings, if the format string walker pointer 'Format' is pointing at the end of the format string (i.e. '\0'), the following expression: *(Format + 1) will read an undefined value. Though this value won't affect the functionality, since it will be masked by variable 'FormatMask': (*(Format + 1) << 8)) & FormatMask (FormatMask is 0xff for ASCII format string) This commit adds additional logic to avoid reading undefined content. Cc: Jiewen Yao Cc: Liming Gao Cc: Michael Kinney Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Hao Wu --- MdePkg/Library/BasePrintLib/PrintLibInternal.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/MdePkg/Library/BasePrintLib/PrintLibInternal.c b/MdePkg/Librar= y/BasePrintLib/PrintLibInternal.c index 9b15a07ac0..cec5b3bc99 100644 --- a/MdePkg/Library/BasePrintLib/PrintLibInternal.c +++ b/MdePkg/Library/BasePrintLib/PrintLibInternal.c @@ -653,7 +653,7 @@ BasePrintLibSPrintMarker ( // // Get the first character from the format string // - FormatCharacter =3D ((*Format & 0xff) | (*(Format + 1) << 8)) & FormatMa= sk; + FormatCharacter =3D ((*Format & 0xff) | ((BytesPerFormatCharacter =3D=3D= 1) ? 0 : (*(Format + 1) << 8))) & FormatMask; =20 // // Loop until the end of the format string is reached or the output buff= er is full @@ -685,7 +685,7 @@ BasePrintLibSPrintMarker ( // for (Done =3D FALSE; !Done; ) { Format +=3D BytesPerFormatCharacter; - FormatCharacter =3D ((*Format & 0xff) | (*(Format + 1) << 8)) & Fo= rmatMask; + FormatCharacter =3D ((*Format & 0xff) | ((BytesPerFormatCharacter = =3D=3D 1) ? 0 : (*(Format + 1) << 8))) & FormatMask; switch (FormatCharacter) { case '.':=20 Flags |=3D PRECISION;=20 @@ -738,7 +738,7 @@ BasePrintLibSPrintMarker ( for (Count =3D 0; ((FormatCharacter >=3D '0') && (FormatCharact= er <=3D '9')); ){ Count =3D (Count * 10) + FormatCharacter - '0'; Format +=3D BytesPerFormatCharacter; - FormatCharacter =3D ((*Format & 0xff) | (*(Format + 1) << 8)) = & FormatMask; + FormatCharacter =3D ((*Format & 0xff) | ((BytesPerFormatCharac= ter =3D=3D 1) ? 0 : (*(Format + 1) << 8))) & FormatMask; } Format -=3D BytesPerFormatCharacter; if ((Flags & PRECISION) =3D=3D 0) { @@ -1017,7 +1017,7 @@ BasePrintLibSPrintMarker ( =20 case '\r': Format +=3D BytesPerFormatCharacter; - FormatCharacter =3D ((*Format & 0xff) | (*(Format + 1) << 8)) & Fo= rmatMask; + FormatCharacter =3D ((*Format & 0xff) | ((BytesPerFormatCharacter = =3D=3D 1) ? 0 : (*(Format + 1) << 8))) & FormatMask; if (FormatCharacter =3D=3D '\n') { // // Translate '\r\n' to '\r\n' @@ -1038,7 +1038,7 @@ BasePrintLibSPrintMarker ( // ArgumentString =3D "\r\n"; Format +=3D BytesPerFormatCharacter; - FormatCharacter =3D ((*Format & 0xff) | (*(Format + 1) << 8)) & Fo= rmatMask; + FormatCharacter =3D ((*Format & 0xff) | ((BytesPerFormatCharacter = =3D=3D 1) ? 0 : (*(Format + 1) << 8))) & FormatMask; if (FormatCharacter !=3D '\r') { Format -=3D BytesPerFormatCharacter; } @@ -1057,7 +1057,7 @@ BasePrintLibSPrintMarker ( =20 case '\r': Format +=3D BytesPerFormatCharacter; - FormatCharacter =3D ((*Format & 0xff) | (*(Format + 1) << 8)) & Form= atMask; + FormatCharacter =3D ((*Format & 0xff) | ((BytesPerFormatCharacter = =3D=3D 1) ? 0 : (*(Format + 1) << 8))) & FormatMask; if (FormatCharacter =3D=3D '\n') { // // Translate '\r\n' to '\r\n' @@ -1078,7 +1078,7 @@ BasePrintLibSPrintMarker ( // ArgumentString =3D "\r\n"; Format +=3D BytesPerFormatCharacter; - FormatCharacter =3D ((*Format & 0xff) | (*(Format + 1) << 8)) & Form= atMask; + FormatCharacter =3D ((*Format & 0xff) | ((BytesPerFormatCharacter = =3D=3D 1) ? 0 : (*(Format + 1) << 8))) & FormatMask; if (FormatCharacter !=3D '\r') { Format -=3D BytesPerFormatCharacter; } @@ -1206,7 +1206,7 @@ BasePrintLibSPrintMarker ( // // Get the next character from the format string // - FormatCharacter =3D ((*Format & 0xff) | (*(Format + 1) << 8)) & Format= Mask; + FormatCharacter =3D ((*Format & 0xff) | ((BytesPerFormatCharacter =3D= =3D 1) ? 0 : (*(Format + 1) << 8))) & FormatMask; } =20 if ((Flags & COUNT_ONLY_NO_PRINT) !=3D 0) { --=20 2.12.0.windows.1 _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel