On 08/28/2017 07:39 AM, Laszlo Ersek wrote:
There's a small window between - AllocFwCfgDmaAccessBuffer() mapping the new FW_CFG_DMA_ACCESS object for common buffer operation (i.e., decrypting it), and - InternalQemuFwCfgDmaBytes() setting the fields of the object. In this window, earlier garbage in the object is "leaked" to the hypervisor. So zero the object before we decrypt it. (This commit message references AMD SEV directly, because QemuFwCfgDxeLib is not *generally* enabled for IOMMU operation just yet, unlike our goal for the virtio infrastructure. Instead, QemuFwCfgDxeLib uses MemEncryptSevLib explicitly to detect SEV, and then relies on IOMMU protocol behavior that is specific to SEV. At this point, this is by design.) Cc: Brijesh Singh <[email protected]> Cc: Jordan Justen <[email protected]> Cc: Tom Lendacky <[email protected]> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Laszlo Ersek <[email protected]>
Reviewed-by: Brijesh Singh <[email protected]> _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
