From 632e57f0f36d9b48f574db273a19e26bf592fc99 Mon Sep 17 00:00:00 2001 From: Michael Brown Date: Wed, 22 Jun 2016 09:07:20 +0100 Subject: [PATCH] [efi] Do not copy garbage bytes into SNP device path MAC address The SNP device path includes the network device's MAC address within the MAC_ADDR_DEVICE_PATH.MacAddress field. We check that the link-layer address will fit within this field, and then perform the copy using the length of the destination buffer. At 32 bytes, the MacAddress field is actually larger than the current maximum iPXE link-layer address. The copy therefore overflows the source buffer, resulting in trailing garbage bytes being appended to the device path's MacAddress. This is invisible in debug messages, since the DevicePathToText protocol will render only the length implied by the interface type. Fix by copying only the actual length of the link-layer address (which we have already verified will not overflow the destination buffer). Debugged-by: Laszlo Ersek Signed-off-by: Michael Brown --- src/interface/efi/efi_snp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: ipxe/src/interface/efi/efi_snp.c =================================================================== --- ipxe.orig/src/interface/efi/efi_snp.c +++ ipxe/src/interface/efi/efi_snp.c @@ -1049,7 +1049,7 @@ static int efi_snp_probe ( struct net_de macpath->Header.SubType = MSG_MAC_ADDR_DP; macpath->Header.Length[0] = sizeof ( *macpath ); memcpy ( &macpath->MacAddress, netdev->ll_addr, - sizeof ( macpath->MacAddress ) ); + netdev->ll_protocol->ll_addr_len ); macpath->IfType = ntohs ( netdev->ll_protocol->ll_proto ); memset ( path_end, 0, sizeof ( *path_end ) ); path_end->Type = END_DEVICE_PATH_TYPE;