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authorerictian <erictian@6f19259b-4bc3-4df7-8a09-765794883524>2013-04-07 08:43:28 +0000
committererictian <erictian@6f19259b-4bc3-4df7-8a09-765794883524>2013-04-07 08:43:28 +0000
commit7a4d52add105b1af8d414ed7db2fc6bd94d69dcd (patch)
treee21f73f008be9d439c88e00f5bdef16241c8822e /MdeModulePkg
parente79095b7b7d997bd6481a30eb2e7bf7a421a3ca9 (diff)
downloadedk2-platforms-7a4d52add105b1af8d414ed7db2fc6bd94d69dcd.tar.xz
MdeMdeModulePkg/UsbBusDxe: Fixed a possible memory leak bug introduced at r14226
The r14226 check-in indeed has memory leak in allocated "Child" pointer. UsbBusDriverBindingStop() may dereference this pointer and may bring exception on invalid memory access Signed-off-by: Feng Tian <feng.tian@intel.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com> git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14251 6f19259b-4bc3-4df7-8a09-765794883524
Diffstat (limited to 'MdeModulePkg')
-rw-r--r--MdeModulePkg/Bus/Usb/UsbBusDxe/UsbEnumer.c19
1 files changed, 14 insertions, 5 deletions
diff --git a/MdeModulePkg/Bus/Usb/UsbBusDxe/UsbEnumer.c b/MdeModulePkg/Bus/Usb/UsbBusDxe/UsbEnumer.c
index 8340b72de2..0aa896173d 100644
--- a/MdeModulePkg/Bus/Usb/UsbBusDxe/UsbEnumer.c
+++ b/MdeModulePkg/Bus/Usb/UsbBusDxe/UsbEnumer.c
@@ -814,11 +814,20 @@ UsbEnumerateNewDev (
return EFI_SUCCESS;
ON_ERROR:
-
- if (Child != NULL) {
- UsbFreeDevice (Child);
- }
-
+ //
+ // If reach here, it means the enumeration process on a given port is interrupted due to error.
+ // The s/w resources, including the assigned address(Address) and the allocated usb device data
+ // structure(Bus->Devices[Address]), will NOT be freed here. These resources will be freed when
+ // the device is unplugged from the port or DriverBindingStop() is invoked.
+ //
+ // This way is used to co-work with the lower layer EDKII UHCI/EHCI/XHCI host controller driver.
+ // It's mainly because to keep UEFI spec unchanged EDKII XHCI driver have to maintain a state machine
+ // to keep track of the mapping between actual address and request address. If the request address
+ // (Address) is freed here, the Address value will be used by next enumerated device. Then EDKII XHCI
+ // host controller driver will have wrong information, which will cause further transaction error.
+ //
+ // EDKII UHCI/EHCI doesn't get impacted as it's make sense to reserve s/w resource till it gets unplugged.
+ //
return Status;
}