bug/fuse-memory-allocation-failed

[asmrtfm]

SEE: the comment below for triage and workaround

---

Following the instructions on https://xtool.sh/documentation/xtool/installation-linux/

After running:

curl -fL \
  "https://github.com/xtool-org/xtool/releases/latest/download/xtool-$(uname -m).AppImage" \
  -o xtool
chmod +x xtool
sudo mv xtool /usr/local/bin/

When I run:

>  xtool --help

fuse: memory allocation failed
squashfuse 0.5.2 (c) 2012 Dave Vasilevsky

Usage: squashfuse [options] ARCHIVE MOUNTPOINT

# ...squashfuse help information...

Can't open squashfs image: Bad address

Cannot mount AppImage, please check your FUSE setup.
You might still be able to extract the contents of this AppImage 
if you run it with the --appimage-extract option. 
See https://github.com/AppImage/AppImageKit/wiki/FUSE 
for more information
execv error: No such file or directory

Environment

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=22.04
DISTRIB_CODENAME=jammy
DISTRIB_DESCRIPTION="Ubuntu 22.04.5 LTS"
PRETTY_NAME="Ubuntu 22.04.5 LTS"
NAME="Ubuntu"
VERSION_ID="22.04"
VERSION="22.04.5 LTS (Jammy Jellyfish)"
VERSION_CODENAME=jammy
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
UBUNTU_CODENAME=jammy

Swift version:
Swift version 6.3.1 (swift-6.3.1-RELEASE)
Target: x86_64-unknown-linux-gnu

[asmrtfm]

Some additional diagnosis — the AppImage itself is fine, but its bundled runtime is broken on this system in two independent ways.

Environment looks healthy:

• Ubuntu 22.04.5, kernel 6.8.0-111-generic
• libfuse2 2.9.9, libfuse3-3 3.10.5, libsquashfuse0 0.1.103, squashfs-tools 4.5 all installed
• /dev/fuse present (crw-rw-rw-)
• kernel.unprivileged_userns_clone=1, apparmor_restrict_unprivileged_userns=0

The AppImage payload is structurally valid:

• file reports ELF 64-bit LSB pie executable, x86-64, static-pie linked
• Magic at offset 8 is 41 49 02 00 (AI\x02 — type 2 AppImage)
• xtool --appimage-offset correctly reports 944632
• Bytes at offset 944632 are 68 73 71 73 (hsqs — valid squashfs superblock)
• unsquashfs -o 944632 -d out /usr/local/bin/xtool extracts cleanly (66 inodes, 48 dirs, 3 symlinks) and the resulting AppRun runs xtool --help perfectly

What's failing is the bundled runtime:

1. FUSE mount path → fuse: memory allocation failed / Can't open squashfs image: Bad address
2. Fallback path → xtool --appimage-extract exits with This doesn't look like a squashfs image. / Failed to open squashfs image — even though the runtime knows the correct offset and the squashfs magic is right there.

Both code paths in the AppImage runtime fail to read a payload that unsquashfs reads without complaint. That points at a bug in the runtime build shipped with the release (possibly an mmap/MAP_POPULATE or large-allocation issue on 6.8 kernels), not the user's FUSE setup.

For anyone else hitting this, the following workaround, well, works:

unsquashfs -o 944632 -d /tmp/xtool-extracted /usr/local/bin/xtool
sudo mv /tmp/xtool-extracted /opt/xtool
sudo ln -sf /opt/xtool/AppRun /usr/local/bin/xtool
xtool --help