Re: [PATCH v2 6/6] MdeModulePkg/AtaAtapiPassThru: Fix possible out of range left shift

["Zeng, Star" <star.zeng@intel.com>]

Got it, thanks for the information. :)

Star
-----Original Message-----
From: Gao, Liming 
Sent: Thursday, September 28, 2017 11:57 AM
To: Zeng, Star <star.zeng@intel.com>; Wu, Hao A <hao.a.wu@intel.com>; edk2-devel@lists.01.org
Cc: Wu, Hao A <hao.a.wu@intel.com>; Dong, Eric <eric.dong@intel.com>
Subject: RE: [edk2] [PATCH v2 6/6] MdeModulePkg/AtaAtapiPassThru: Fix possible out of range left shift

Star:
 Crc32 change is not required . I just gives my comment on it. So, there is no consistent issue here. We can keep this patch. 

Thanks
Liming
>-----Original Message-----
>From: Zeng, Star
>Sent: Monday, September 25, 2017 2:25 PM
>To: Wu, Hao A <hao.a.wu@intel.com>; edk2-devel@lists.01.org
>Cc: Wu, Hao A <hao.a.wu@intel.com>; Dong, Eric <eric.dong@intel.com>; 
>Gao, Liming <liming.gao@intel.com>; Zeng, Star <star.zeng@intel.com>
>Subject: RE: [edk2] [PATCH v2 6/6] MdeModulePkg/AtaAtapiPassThru: Fix 
>possible out of range left shift
>
>I prefer to have the code consistent between this patch with [PATCH v2 
>5/6]
>MdeModulePkg/Crc32: Fix possible out of range left shift.
>
>Both to use (UINT32) typecast or 1U.
>
>Liming, Do you have any comment?
>
>
>Thanks,
>Star
>-----Original Message-----
>From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of 
>Hao Wu
>Sent: Thursday, September 21, 2017 2:46 PM
>To: edk2-devel@lists.01.org
>Cc: Wu, Hao A <hao.a.wu@intel.com>; Dong, Eric <eric.dong@intel.com>; 
>Zeng, Star <star.zeng@intel.com>
>Subject: [edk2] [PATCH v2 6/6] MdeModulePkg/AtaAtapiPassThru: Fix 
>possible out of range left shift
>
>REF: https://bugzilla.tianocore.org/show_bug.cgi?id=699
>
>Within function AhciModeInitialization(), left shift operations of 'BIT0'
>in the following statements:
>"if ((PortImplementBitMap & (BIT0 << Port)) != 0) {"
>
>will incur possible out of range left shift when Port is 31, since
>"1 << 31" is possible to exceed the range of type 'int' (signed).
>
>According to the C11 spec, Section 6.5.7:
>> 4 The result of E1 << E2 is E1 left-shifted E2 bit positions; vacated
>>   bits are filled with zeros. If E1 has an unsigned type, the value
>>   of the result is E1 * 2^E2 , reduced modulo one more than the
>>   maximum value representable in the result type. If E1 has a signed
>>   type and nonnegative value, and E1 * 2^E2 is representable in the
>>   result type, then that is the resulting value; otherwise, the
>>   behavior is undefined.
>
>This commit explicitly cast 'BIT0' with UINT32 to resolve this issue.
>
>Cc: Steven Shi <steven.shi@intel.com>
>Cc: Star Zeng <star.zeng@intel.com>
>Cc: Eric Dong <eric.dong@intel.com>
>Contributed-under: TianoCore Contribution Agreement 1.1
>Signed-off-by: Hao Wu <hao.a.wu@intel.com>
>---
> MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AhciMode.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AhciMode.c
>b/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AhciMode.c
>index b954de8101..e6de5d65bc 100644
>--- a/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AhciMode.c
>+++ b/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/AhciMode.c
>@@ -1,7 +1,7 @@
> /** @file
>   The file for AHCI mode of ATA host controller.
>
>-  Copyright (c) 2010 - 2016, Intel Corporation. All rights 
>reserved.<BR>
>+  Copyright (c) 2010 - 2017, Intel Corporation. All rights 
>+ reserved.<BR>
>   (C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
>   This program and the accompanying materials
>   are licensed and made available under the terms and conditions of 
>the BSD License @@ -2314,7 +2314,7 @@ AhciModeInitialization (
>   }
>
>   for (Port = 0; Port < EFI_AHCI_MAX_PORTS; Port ++) {
>-    if ((PortImplementBitMap & (BIT0 << Port)) != 0) {
>+    if ((PortImplementBitMap & (((UINT32)BIT0) << Port)) != 0) {
>       //
>       // According to AHCI spec, MaxPortNumber should be equal or 
>greater than the number of implemented ports.
>       //
>--
>2.12.0.windows.1
>
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