From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) (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 F1D4321D2E623 for ; Wed, 23 Aug 2017 19:54:16 -0700 (PDT) Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 23 Aug 2017 19:56:51 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.41,419,1498546800"; d="scan'208";a="127635419" Received: from ydong10-win10.ccr.corp.intel.com ([10.239.158.51]) by orsmga002.jf.intel.com with ESMTP; 23 Aug 2017 19:56:49 -0700 From: Eric Dong To: edk2-devel@lists.01.org Cc: Michael Kinney , Ruiyu Ni Date: Thu, 24 Aug 2017 10:56:47 +0800 Message-Id: <1503543407-7936-1-git-send-email-eric.dong@intel.com> X-Mailer: git-send-email 2.7.0.windows.1 Subject: [Patch] UefiCpuPkg/MpLib: fix potential overflow issue. 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: , X-List-Received-Date: Thu, 24 Aug 2017 02:54:17 -0000 Current calculate timeout logic may have overflow if the input timeout value too large. This patch fix this potential overflow issue. V2: Use local variable instead of call GetPerformanceCounterProperties twice. Also correct some comments. Cc: Michael Kinney Cc: Ruiyu Ni Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Eric Dong --- UefiCpuPkg/Library/MpInitLib/MpLib.c | 43 +++++++++++++++++++++++++++--------- 1 file changed, 33 insertions(+), 10 deletions(-) diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c index ed1f55e..8394572 100644 --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c @@ -1001,6 +1001,9 @@ CalculateTimeout ( OUT UINT64 *CurrentTime ) { + UINT64 TimeoutInSeconds; + UINT64 TimestampCounterFreq; + // // Read the current value of the performance counter // @@ -1016,16 +1019,36 @@ CalculateTimeout ( // // GetPerformanceCounterProperties () returns the timestamp counter's frequency - // in Hz. So multiply the return value with TimeoutInMicroseconds and then divide - // it by 1,000,000, to get the number of ticks for the timeout value. - // - return DivU64x32 ( - MultU64x64 ( - GetPerformanceCounterProperties (NULL, NULL), - TimeoutInMicroseconds - ), - 1000000 - ); + // in Hz. + // + TimestampCounterFreq = GetPerformanceCounterProperties (NULL, NULL); + + // + // Check the potential overflow before calculate the number of ticks for the timeout value. + // + if (DivU64x64Remainder (MAX_UINT64, TimeoutInMicroseconds, NULL) < TimestampCounterFreq) { + // + // Convert microseconds into seconds if direct multiplication overflows + // + TimeoutInSeconds = DivU64x32 (TimeoutInMicroseconds, 1000000); + // + // Assertion if the final tick count exceeds MAX_UINT64 + // + ASSERT (DivU64x64Remainder (MAX_UINT64, TimeoutInSeconds, NULL) >= TimestampCounterFreq); + return MultU64x64 (TimestampCounterFreq, TimeoutInSeconds); + } else { + // + // No overflow case, multiply the return value with TimeoutInMicroseconds and then divide + // it by 1,000,000, to get the number of ticks for the timeout value. + // + return DivU64x32 ( + MultU64x64 ( + TimestampCounterFreq, + TimeoutInMicroseconds + ), + 1000000 + ); + } } /** -- 2.7.0.windows.1