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From: "Zeng, Star" <star.zeng@intel.com>
To: Guoheyi <guoheyi@huawei.com>,
	"edk2-devel@lists.01.org" <edk2-devel@lists.01.org>
Cc: "Tian, Feng" <feng.tian@intel.com>, "Zeng, Star" <star.zeng@intel.com>
Subject: Re: [ScsiDiskDxe] Implict type conversion bug
Date: Mon, 10 Apr 2017 09:48:11 +0000	[thread overview]
Message-ID: <0C09AFA07DD0434D9E2A0C6AEB0483103B879151@shsmsx102.ccr.corp.intel.com> (raw)
In-Reply-To: <B328F08581D714418202ABF306D3781C3AC13686@DGGEMA505-MBS.china.huawei.com>

Hao has sent patch for this issue.
You can search emails with title "[edk2] [PATCH] MdeModulePkg/ScsiDiskDxe: Fix potential implicit sign extension".

Thanks,
Star
-----Original Message-----
From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Guoheyi
Sent: Monday, April 10, 2017 5:40 PM
To: edk2-devel@lists.01.org
Cc: Tian, Feng <feng.tian@intel.com>
Subject: [edk2] [ScsiDiskDxe] Implict type conversion bug

Hi folks,

In MdeModulePkg/Bus/Scsi/ScsiDiskDxe/ScsiDisk.c, Line 2757, we have the code as below:

    ScsiDiskDevice->BlkIo.Media->LastBlock =  (Capacity10->LastLba3 << 24) |
                                              (Capacity10->LastLba2 << 16) |
                                              (Capacity10->LastLba1 << 8)  |
                                               Capacity10->LastLba0;

However, we tested on VS2008 and found that the intermediate result would be convert to INT32 then INT64 implicitly, so the result will be sign extended and LastBlock may not be assigned with what is expected. We can simply test LastLba3 >= 0x80 to see what will happen.

Please let me know your comments.

Thanks and regards,

Gary (Heyi Guo)
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  reply	other threads:[~2017-04-10  9:48 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-10  9:40 [ScsiDiskDxe] Implict type conversion bug Guoheyi
2017-04-10  9:48 ` Zeng, Star [this message]
2017-04-11  4:24   ` 答复: " Guoheyi
2017-04-11  7:05   ` Guoheyi
2017-04-11  7:13     ` Wu, Hao A

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