From 52758e16e0d1e67b3cdd56e04abfce663607ac42 Mon Sep 17 00:00:00 2001 From: Bhasker Hariharan Date: Mon, 16 Mar 2020 08:02:05 -0700 Subject: Prevent vnetHdr from escaping in WritePacket. PiperOrigin-RevId: 301157950 --- pkg/tcpip/link/fdbased/endpoint.go | 2 +- pkg/tcpip/link/fdbased/endpoint_unsafe.go | 9 +++++---- 2 files changed, 6 insertions(+), 5 deletions(-) diff --git a/pkg/tcpip/link/fdbased/endpoint.go b/pkg/tcpip/link/fdbased/endpoint.go index a753fb243..3b36b9673 100644 --- a/pkg/tcpip/link/fdbased/endpoint.go +++ b/pkg/tcpip/link/fdbased/endpoint.go @@ -407,7 +407,6 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, protocol tcpip.Ne if e.Capabilities()&stack.CapabilityHardwareGSO != 0 { vnetHdr := virtioNetHdr{} - vnetHdrBuf := vnetHdrToByteSlice(&vnetHdr) if gso != nil { vnetHdr.hdrLen = uint16(pkt.Header.UsedLength()) if gso.NeedsCsum { @@ -428,6 +427,7 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, protocol tcpip.Ne } } + vnetHdrBuf := vnetHdrToByteSlice(&vnetHdr) return rawfile.NonBlockingWrite3(e.fds[0], vnetHdrBuf, pkt.Header.View(), pkt.Data.ToView()) } diff --git a/pkg/tcpip/link/fdbased/endpoint_unsafe.go b/pkg/tcpip/link/fdbased/endpoint_unsafe.go index 97a477b61..d81858353 100644 --- a/pkg/tcpip/link/fdbased/endpoint_unsafe.go +++ b/pkg/tcpip/link/fdbased/endpoint_unsafe.go @@ -24,9 +24,10 @@ import ( const virtioNetHdrSize = int(unsafe.Sizeof(virtioNetHdr{})) func vnetHdrToByteSlice(hdr *virtioNetHdr) (slice []byte) { - sh := (*reflect.SliceHeader)(unsafe.Pointer(&slice)) - sh.Data = uintptr(unsafe.Pointer(hdr)) - sh.Len = virtioNetHdrSize - sh.Cap = virtioNetHdrSize + *(*reflect.SliceHeader)(unsafe.Pointer(&slice)) = reflect.SliceHeader{ + Data: uintptr((unsafe.Pointer(hdr))), + Len: virtioNetHdrSize, + Cap: virtioNetHdrSize, + } return } -- cgit v1.2.3