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An update is available to fix a data corruption issue for Secure Digital (SD) cards in Windows 7

Article ID: 976092 - View products that this article applies to.

Introduction

This article describes a Windows 7 update that fixes a data corruption issue that occurs in Secure Digital (SD) cards.

You have an NTFS-formatted SD card. You use Advanced Direct Memory Access (ADMA) to transfer data between the SD card and a computer that is running Windows 7. However, during this operation, the data on the SD card may be corrupted. Additionally, unexpected problems may occur when you try to use the affected data.

During an ADMA transfer process, the Secure Digital Bus Driver (Sdbus.sys) converts the DMA data structure of the operating system to the ADMA data structure of the SD card. The DMA and the ADMA data structures are also known as descriptor tables. A descriptor table contains a data length value and a buffer address. The data-length field is 16-bit, and it has a maximum size of 64 kilobytes (KB). However, during the data conversion process, the Sdbus.sys driver does not check the buffer size in the descriptor table of the system. Therefore, the Sdbus.sys driver may set an incorrect data length in the SD descriptor table. For example, the Sdbus.sys driver may set the data length to something longer than 0xFFFF. Also, I/O corruption occurs, in this scenario. This, in turn, causes data corruption.

Update information

You can download this update from the Microsoft Update Web site or from the Windows Download Center.

Windows Update Web site

http://update.microsoft.com

(http://update.microsoft.com)

Windows Download Center

The following files are available for download from the Microsoft Download Center:

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Operating system	Update
All supported x86-based versions of Windows 7	Collapse this imageExpand this image Download the update package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=c7494e1d-81d4-4974-a268-6ec0a71d12f9)
All supported x64-based versions of Windows 7	Collapse this imageExpand this image Download the update package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=3b104619-6389-4065-812d-2d9233f59852)

For more information about how to download Microsoft support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591

(http://support.microsoft.com/kb/119591/ )

How to obtain Microsoft support files from online services

Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help prevent any unauthorized changes to the file.

Prerequisites

There are no prerequisites to apply this update.

Registry information

To use the update in this package, you do not have to make any changes to the registry.

Restart requirement

You must restart the computer after you apply this update.

Update replacement information

This update does not replace a previously released update.

File information

The English (United States) version of this update installs files that have the attributes that are listed in the following tables. The dates and times for these files are listed in Coordinated Universal Time (UTC). The dates and times for these files on your local computer are displayed in your local time and with your current daylight saving time (DST) bias. Additionally, the dates and times may change when you perform certain operations on the files.

Windows 7 file information notes

The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
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Version Product Milestone Service branch
6.1.760 0.16xxx Windows 7 RTM GDR
6.1.760 0.20xxx Windows 7 RTM LDR
GDR service branches contain only those fixes that are widely released to address widespread, critical issues. LDR service branches contain hotfixes in addition to widely released fixes.