答复: [ScsiDiskDxe] Implict type conversion bug

[Guoheyi <guoheyi@huawei.com>]

Thanks for your quick fix :)

-----邮件原件-----
发件人: Zeng, Star [mailto:star.zeng@intel.com] 
发送时间: 2017年4月10日 17:48
收件人: Guoheyi; edk2-devel@lists.01.org
抄送: Tian, Feng; Zeng, Star
主题: RE: [edk2] [ScsiDiskDxe] Implict type conversion bug

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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