[Bug 2105467] [NEW] lshw -C network hangs indefinitely on Ubuntu 24.04.2 with virtual interfaces (tailscale0, docker0, vmnet, etc.)

[Peter Goodall]

Public bug reported:

Summary:
lshw -C network hangs indefinitely on Ubuntu 24.04.2 with virtual interfaces such as tailscale0, docker0, vmnet*, and lxcbr0

❯ lsb_release -rd
No LSB modules are available.
Description:	Ubuntu 24.04.2 LTS
Release:	24.04

❯ apt-cache policy lshw
lshw:
  Installed: 02.19.git.2021.06.19.996aaad9c7-2build3
  Candidate: 02.19.git.2021.06.19.996aaad9c7-2build3
  Version table:
 *** 02.19.git.2021.06.19.996aaad9c7-2build3 500
        500 http://archive.ubuntu.com/ubuntu noble/main amd64 Packages
        500 http://ubuntu.mirror.serversaustralia.com.au/ubuntu noble/main amd64 Packages
        100 /var/lib/dpkg/status

Description:
On Ubuntu 24.04.2 with kernel 6.8.0-56-generic, the lshw command hangs when scanning network interfaces. This occurs even when filtering for known-good PCI devices.

Running sudo lshw -C network produces no output and does not complete.
Adding timeouts (e.g. timeout 10s sudo lshw -C network) confirms it does
not return.

The installed version is:

lshw: 02.19.git.2021.06.19.996aaad9c7-2build3

The package passes verification (sudo dpkg -V lshw) and has no missing
files.

lspci and /sys/class/net show that there are two valid PCI interfaces
(eno1 and ens1). However, lshw appears to probe all interfaces under
/sys/class/net/* before filtering, and hangs or exits silently when
encountering virtual interfaces that lack a device/uevent, such as:

docker0 (Docker bridge)

tailscale0 (Tailscale)

lxcbr0 (LXC bridge)

vmnet1, vmnet2, vmnet8 (VMware Workstation)

br-* (custom Docker bridge)

Manual probing of /sys/class/net/*/device/uevent confirms that these
interfaces do not have hardware backing, which causes lshw to fail
silently or stall.

This behavior breaks system administration scripts and diagnostics.
Previous versions of lshw (and tools like lspci, ethtool, etc.) handled
these interfaces gracefully.

Expected behavior:
lshw should gracefully skip virtual interfaces without a device/uevent, or timeout quickly rather than hanging indefinitely.

How to reproduce:

Use Ubuntu 24.04.2 with kernel 6.8.0-56-generic

Install Docker, Tailscale, VMware Workstation or any software that
creates virtual interfaces

Run: sudo lshw -C network

Observe that the command hangs or exits with no output

Workaround:
Avoid using lshw on systems with active virtual interfaces. Use lspci, ethtool, and udevadm instead to inspect network hardware.

Some help by ChatGPT in producing this

** Affects: lshw (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/2105467

Title:
  lshw -C network hangs indefinitely on Ubuntu 24.04.2 with virtual
  interfaces (tailscale0, docker0, vmnet, etc.)

Status in lshw package in Ubuntu:
  New

Bug description:
  Summary:
  lshw -C network hangs indefinitely on Ubuntu 24.04.2 with virtual interfaces such as tailscale0, docker0, vmnet*, and lxcbr0

  ❯ lsb_release -rd
  No LSB modules are available.
  Description:	Ubuntu 24.04.2 LTS
  Release:	24.04

  ❯ apt-cache policy lshw
  lshw:
    Installed: 02.19.git.2021.06.19.996aaad9c7-2build3
    Candidate: 02.19.git.2021.06.19.996aaad9c7-2build3
    Version table:
   *** 02.19.git.2021.06.19.996aaad9c7-2build3 500
          500 http://archive.ubuntu.com/ubuntu noble/main amd64 Packages
          500 http://ubuntu.mirror.serversaustralia.com.au/ubuntu noble/main amd64 Packages
          100 /var/lib/dpkg/status

  Description:
  On Ubuntu 24.04.2 with kernel 6.8.0-56-generic, the lshw command hangs when scanning network interfaces. This occurs even when filtering for known-good PCI devices.

  Running sudo lshw -C network produces no output and does not complete.
  Adding timeouts (e.g. timeout 10s sudo lshw -C network) confirms it
  does not return.

  The installed version is:

  lshw: 02.19.git.2021.06.19.996aaad9c7-2build3

  The package passes verification (sudo dpkg -V lshw) and has no missing
  files.

  lspci and /sys/class/net show that there are two valid PCI interfaces
  (eno1 and ens1). However, lshw appears to probe all interfaces under
  /sys/class/net/* before filtering, and hangs or exits silently when
  encountering virtual interfaces that lack a device/uevent, such as:

  docker0 (Docker bridge)

  tailscale0 (Tailscale)

  lxcbr0 (LXC bridge)

  vmnet1, vmnet2, vmnet8 (VMware Workstation)

  br-* (custom Docker bridge)

  Manual probing of /sys/class/net/*/device/uevent confirms that these
  interfaces do not have hardware backing, which causes lshw to fail
  silently or stall.

  This behavior breaks system administration scripts and diagnostics.
  Previous versions of lshw (and tools like lspci, ethtool, etc.)
  handled these interfaces gracefully.

  Expected behavior:
  lshw should gracefully skip virtual interfaces without a device/uevent, or timeout quickly rather than hanging indefinitely.

  How to reproduce:

  Use Ubuntu 24.04.2 with kernel 6.8.0-56-generic

  Install Docker, Tailscale, VMware Workstation or any software that
  creates virtual interfaces

  Run: sudo lshw -C network

  Observe that the command hangs or exits with no output

  Workaround:
  Avoid using lshw on systems with active virtual interfaces. Use lspci, ethtool, and udevadm instead to inspect network hardware.

  Some help by ChatGPT in producing this

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