syscall: ParseNetlinkMessage does not check boundaries before slice reference

[david415]

Please answer these questions before submitting your issue. Thanks!

1. What version of Go are you using (go version)?
   go-1.6
2. What operating system and processor architecture are you using (go env)?
   GOARCH="amd64"
   GOBIN=""
   GOEXE=""
   GOHOSTARCH="amd64"
   GOHOSTOS="linux"
   GOOS="linux"
   GOPATH="/home/user/gopath"
   GORACE=""
   GOROOT="/usr/lib/go-1.6"
   GOTOOLDIR="/usr/lib/go-1.6/pkg/tool/linux_amd64"
   GO15VENDOREXPERIMENT="1"
   CC="gcc"
   GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0"
   CXX="g++"
   CGO_ENABLED="1"
3. What did you do?
   If possible, provide a recipe for reproducing the error.
   A complete runnable program is good.
   A link on play.golang.org is best.

I've written a complete description of how I exercise golang's syscall module's netlink message parsing bug here:
subgraph/go-nfnetlink#1

The problem is that the slice boundaries are not checked to make sure they do not extend past the end of the slice, here:

go/src/syscall/netlink_linux.go

Line 125 in 31ad583

b = b[dlen:]

1. What did you expect to see?

Bounds checking and a proper error, returned.

1. What did you see instead?

I saw buggy network parsing code.

[gopherbot]

CL https://golang.org/cl/26990 mentions this issue.