Re: [Patch] MdeModulePkg/UsbMassStorageDxe: Verify Get Max LUN value

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

Reviewed-by: Star Zeng <star.zeng@intel.com>

How about also adding the compatibility info(now in commit log) to the code comments?
For example,

+    //
+    // If MaxLun is larger than the maximum LUN value (0x0f) supported by the
+    // USB Mass Storage Class Bulk-Only Transport Spec, then set MaxLun to 0
+    // which means no LUN is associated with the device.
+    // It improves compatibility with USB FLASH drives that have a single LUN,
+    // but return invalid maximum LUN values.
+    //

Thanks,
Star
-----Original Message-----
From: Kinney, Michael D 
Sent: Thursday, November 9, 2017 6:19 AM
To: edk2-devel@lists.01.org
Cc: Zeng, Star <star.zeng@intel.com>; Dong, Eric <eric.dong@intel.com>
Subject: [Patch] MdeModulePkg/UsbMassStorageDxe: Verify Get Max LUN value

The USB Mass Storage Class Specification states that a maximum LUN value larger than 0x0F is invalid.  Add a check to make sure this maximum LUN value is in this valid range, and if it is not, then assume that the device does not support multiple LUNs and return a maximum LUN value of 0.

This change improves compatibility with USB FLASH drives that have a single LUN, but return invalid maximum LUN values.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
---
 MdeModulePkg/Bus/Usb/UsbMassStorageDxe/UsbMassBot.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/MdeModulePkg/Bus/Usb/UsbMassStorageDxe/UsbMassBot.c b/MdeModulePkg/Bus/Usb/UsbMassStorageDxe/UsbMassBot.c
index 4bb7222b89..c7436cf036 100644
--- a/MdeModulePkg/Bus/Usb/UsbMassStorageDxe/UsbMassBot.c
+++ b/MdeModulePkg/Bus/Usb/UsbMassStorageDxe/UsbMassBot.c
@@ -2,7 +2,7 @@
   Implementation of the USB mass storage Bulk-Only Transport protocol,
   according to USB Mass Storage Class Bulk-Only Transport, Revision 1.0.
 
-Copyright (c) 2007 - 2011, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2007 - 2017, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials  are licensed and made available under the terms and conditions of the BSD License  which accompanies this distribution.  The full text of the license may be found at @@ -576,6 +576,14 @@ UsbBotGetMaxLun (
                             1,
                             &Result
                             );
+  if (!EFI_ERROR (Status) && *MaxLun > USB_BOT_MAX_LUN) {
+    //
+    // If MaxLun is larger than the maximum LUN value (0x0f) supported by the
+    // USB Mass Storage Class Bulk-Only Transport Spec, then set MaxLun to 0
+    // which means no LUN is associated with the device.
+    //
+    *MaxLun = 0;
+  }
 
   return Status;
 }
--
2.14.2.windows.3