panic when using wrong detach keys

[vieux]

docker run --cpus 0.5 --name test -itd busybox sh -c "ping google.com"

docker attach --detach-keys="ctrl-A,a" test

the attach works on 17.06 but panics on 17.07

 panic: runtime error: invalid memory address or nil pointer dereference
 [signal SIGSEGV: segmentation violation code=0x1 addr=0x28 pc=0x4139376]

 goroutine 12 [running]:
 bufio.(*Reader).writeBuf(0x0, 0x4fad960, 0xc42037ccc0, 0xc42002fe48, 0x400f69d, 0x49c3b40)
 	/usr/local/go/src/bufio/bufio.go:504 +0x26
 bufio.(*Reader).WriteTo(0x0, 0x4fad960, 0xc42037ccc0, 0x5540198, 0x0, 0x1)
 	/usr/local/go/src/bufio/bufio.go:462 +0x43
 io.copyBuffer(0x4fad960, 0xc42037ccc0, 0x4fad260, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
 	/usr/local/go/src/io/io.go:380 +0x31a
 io.Copy(0x4fad960, 0xc42037ccc0, 0x4fad260, 0x0, 0x0, 0x0, 0x0)
 	/usr/local/go/src/io/io.go:360 +0x68
 github.com/docker/cli/cli/command/container.(*hijackedIOStreamer).beginOutputStream.func1(0xc420405e30, 0xc42045ac20, 0xc42041af60)
 	/go/src/github.com/docker/cli/cli/command/container/hijack.go:123 +0x200
 created by github.com/docker/cli/cli/command/container.(*hijackedIOStreamer).beginOutputStream
 	/go/src/github.com/docker/cli/cli/command/container/hijack.go:139 +0x83

(sorry for the broken output)

@tiborvass is currently investigating

/cc @jlhawn

[tiborvass]

@vieux It's caused by moby/moby@26231b2

[aaronlehmann]

Is this a panic that would have been caught by integration tests if we ran them against the current CLI version instead of fixing the CLI version at an arbitrary point?

[seemethere]

This error still exists with Docker 17.07.0-ce

[vieux]

@seemethere yes, updated the code on moby/moby, but the fix the issue we need to vendor this code in docker/cli

[dnephin]

The fix was vendored as part of of #424

We just need it cherry-picked in docker-ce (docker-archive/docker-ce#221)

[andrewhsu]

@vieux should be --cpus:

docker run --cpus 0.5 --name test -itd busybox sh -c "ping google.com"

[vieux]

@andrewhsu right, but the panic still exists.

[vieux]

fixed in #424