Podman run blocks in isPathOnVolume function forever

[bacher09]

Is this a BUG REPORT or FEATURE REQUEST? (leave only one on its own line)

/kind bug

Description

There is a bug in current isPathOnVolume function which in some cases leads to infinite loop which causes some commands to stuck. This happens cause filepath.Dir(dest) could return . in some cases and calling same method again would return same result (.).

Steps to reproduce the issue:

1. Create a Docker image using this Dockerfile:

cat Dockerfile 
FROM alpine:3.12
VOLUME ['/etc/foo']
WORKDIR /etc/foo
CMD ["echo", "test"]

it can be compiled using any tool (I used original docker build).
NOTE: that VOLUME uses single quotes ' and not ".

2. Pull that image into your system and make it available for podman

3. Try to start that container using that image:

podman run testimg

and this would stuck forever in the loop.

Describe the results you received:

podman run testimg got stuck consuming cpu resources.

Describe the results you expected:

It should either fail or succeed. Interestingly spec like this works fine in a docker, it also used to work in a podman version 2.

Extra information

Basically using single quotes causes vol.Dest to become [/etc/foo] string and calling filepath.Dir on it will eventually return [ and then . so will never match /.

I skipped some fields cause these are not really necessary cause issue is really issue to reproduce.

[bacher09]

The simplest fix would be something like this:

diff --git a/libpod/container_path_resolution.go b/libpod/container_path_resolution.go
index d798963b1..ec7306ca1 100644
--- a/libpod/container_path_resolution.go
+++ b/libpod/container_path_resolution.go
@@ -128,7 +128,7 @@ func isPathOnVolume(c *Container, containerPath string) bool {
                if cleanedContainerPath == filepath.Clean(vol.Dest) {
                        return true
                }
-               for dest := vol.Dest; dest != "/"; dest = filepath.Dir(dest) {
+               for dest := vol.Dest; dest != "/" && dest != "."; dest = filepath.Dir(dest) {
                        if cleanedContainerPath == dest {
                                return true
                        }

which should ensure that it would never loop forever in that code. But also IMHO it would be nice to have some validation for volume as well.

[mheon]

@vrothberg PTAL

[rhatdan]

@bacher09 Please open a PR to fix this?