Hi Ying Guo,
Thanks for capturing this. I agree this is a bug and need be fixed. I will
follow up to fix this soon.
Best Regards,
Ting
From: Ying Guo [mailto:guoyin...@gmail.com]
Sent: Wednesday, July 15, 2015 4:11 PM
To: edk2-devel@lists.sourceforge.net
Subject: [edk2] A possible bug in iSCSI driver implementation
I'm using VMWare EFI firmware to test one project, since the UEFI firmware
currently implemented by VMWware doesn't have a iSCSI driver, so I built the
iSCSI driver from EDK2, and load / connect to VMWare driver stack. After driver
was loaded, I found the firmware stopped responding while I tried to execute
"connect -r" in shell . It looks like very much a dead loop happend somewhere
since I observed that the CPU usage by VMWare is abnormally hight when it
happens.
Afrer few days of investigating (I'm a newbee to UEFI), I noticed that in the
implementation of iSCSI driver, in the file IScsiMisc.c function
IScsiGetTcpConnDevicePath, it copies the gateway and subnetmask to device path
in the code like below:
IP4_COPY_ADDRESS (
&DPathNode->Ipv4.GatewayIpAddress,
&Session->ConfigData.NvData.Gateway
);
IP4_COPY_ADDRESS (
&DPathNode->Ipv4.SubnetMask,
&Session->ConfigData.NvData.SubnetMask
);
However, in the case of underlying IP4 was implemented with older UEFI
spcecification like the VMWare firmware, the IPv4_DEVICE_PATH have neighter
GatewayIpAddress nor SubnetMask, and the Length is 19, rather that 27 defined
in latest UEFI specification. Copying the gateway and subnetmask will break the
device path array. Thus in a upper layer driver, namly SCSIBus driver, it will
get into a infinite loop when the driver tries to iterate through the nodes of
device path, which is broken.
So I suggest to check the length of IP4 node before copying gateway and
subnetmask into the node, in this way the iSCSI driver can be used in older
implemenation of UEFI firmwares. This may apply to files in both NetworkPkg and
MdeModulePkg.
Regards,
Ying Guo
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