CLI `--help` crashes with SIGBUS (Misaligned address error) #787

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opened 2025-04-04 04:39:32 +00:00 by ian-h-chamberlain · 1 comment

ian-h-chamberlain commented

2025-04-04 04:39:32 +00:00

Describe the bug

All my attempts to show CLI help crash with SIGBUS.

§ nix --help 
fish: Job 1, 'nix --help' terminated by signal SIGBUS (Misaligned address error)

Steps To Reproduce

nix --help, or any subcommand also seems to reproduce (e.g. nix flake --help).

Expected behavior

Normal help output is displayed, no crash

`nix --version` output

nix (Lix, like Nix) 2.93.0-dev-pre20250316-2a33681
System type: aarch64-darwin
Additional system types: x86_64-darwin
Features: gc, signed-caches
System configuration file: /etc/nix/nix.conf
User configuration files: /Users/ianchamberlain/.config/nix/nix.conf:/Users/ianchamberlain/.nix-profile/etc/xdg/nix/nix.conf:/run/current-system/sw/etc/xdg/nix/nix.conf:/nix/var/nix/profiles/default/etc/xdg/nix/nix.conf
Store directory: /nix/store
State directory: /nix/var/nix
Data directory: /nix/store/7ric722pdx1a4asyrzqaqflqk58hq2q5-lix-2.93.0-dev-pre20250316-2a33681/share

Additional context

`nix.conf`

# WARNING: this file is generated from the nix.settings option in
# your Home Manager configuration at $XDG_CONFIG_HOME/nix/nix.conf.
# Do not edit it!
extra-experimental-features = repl-flake pipe-operator lix-custom-sub-commands
extra-plugin-files = /Users/ianchamberlain/.config/nix/plugins
repl-overlays = /Users/ianchamberlain/.config/nix/repl-overlays.nix

Lix-module

I am using the lix-module.overlays.default with nix-darwin plus a small custom overlay to disable some tests that kept failing:

(final: prev: {
    lix = prev.lix.override {
      aws-sdk-cpp = prev.aws-sdk-cpp.overrideAttrs (old: {
        cmakeFlags = [ "-DENABLE_TESTING=OFF" ]
          ++ old.cmakeFlags or [ ];
      });
    };
})

Lix flake inputs

├───lix: git+https://git.lix.systems/lix-project/lix.git?ref=main&rev=2a336813ad2a4d64d027830507276da32927d215
│   Last modified: 2025-03-16 18:57:11
├───lix-module: https://git.lix.systems/api/v1/repos/lix-project/nixos-module/archive/621aae0f3cceaffa6d73a4fb0f89c08d338d729e.tar.gz?narHash=sha256-NG3IRvRs3u3btVCN861FqHvgOwqcNT/Oy6PBG86F5/E%3D&rev=621aae0f3cceaffa6d73a4fb0f89c08d338d729e
│   Last modified: 2025-01-29 13:54:00

lldb backtrace

(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=2, address=0x1015378d0)
  * frame #0: 0x00000001015378d0 libc++abi.1.dylib`vtable for __cxxabiv1::__si_class_type_info + 16
    frame #1: 0x0000000100decc08 liblixutil.dylib`nix::MultiCommand::toJSON() + 216
    frame #2: 0x00000001000be368 nix`nix::NixArgs::dumpCli() + 108
    frame #3: 0x00000001000bf1a0 nix`nix::showHelp(nix::AsyncIoRoot&, std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>>>, nix::NixArgs&) + 1220
    frame #4: 0x00000001000ba398 nix`nix::mainWrapped(nix::AsyncIoRoot&, int, char**) + 6452
    frame #5: 0x00000001000c4060 nix`std::__1::__function::__func<main::$_0, std::__1::allocator<main::$_0>, void ()>::operator()() + 120
    frame #6: 0x000000010085c148 liblixmain.dylib`nix::handleExceptions(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>> const&, std::__1::function<void ()>) + 392
    frame #7: 0x00000001000c06a0 nix`main + 216
    frame #8: 0x0000000187c2f154 dyld`start + 2476

Strange behavior

To check if it was just an old version bug, I tried running a new Lix version to see if its --help worked, and it did, but somehow this also seems to have resolved my original issue???

Ran version 2.93.0-dev-pre20250401-5a7e9e1 with --help (it works)
Ran version 2.93.0-dev-pre20250316-2a33681 with --help (previously failing, now working)

This seems very odd to me and I can't be sure what's happening, but it suggests maybe this issue is not actually as reproducible as I first thought... also perhaps upgrading will resolve it in the general case so maybe there's nothing really to do here.

## Describe the bug All my attempts to show CLI help crash with `SIGBUS`. ``` § nix --help fish: Job 1, 'nix --help' terminated by signal SIGBUS (Misaligned address error) ``` ## Steps To Reproduce `nix --help`, or any subcommand also seems to reproduce (e.g. `nix flake --help`). ## Expected behavior Normal help output is displayed, no crash ## `nix --version` output ``` nix (Lix, like Nix) 2.93.0-dev-pre20250316-2a33681 System type: aarch64-darwin Additional system types: x86_64-darwin Features: gc, signed-caches System configuration file: /etc/nix/nix.conf User configuration files: /Users/ianchamberlain/.config/nix/nix.conf:/Users/ianchamberlain/.nix-profile/etc/xdg/nix/nix.conf:/run/current-system/sw/etc/xdg/nix/nix.conf:/nix/var/nix/profiles/default/etc/xdg/nix/nix.conf Store directory: /nix/store State directory: /nix/var/nix Data directory: /nix/store/7ric722pdx1a4asyrzqaqflqk58hq2q5-lix-2.93.0-dev-pre20250316-2a33681/share ``` ## Additional context ### `nix.conf` ``` # WARNING: this file is generated from the nix.settings option in # your Home Manager configuration at $XDG_CONFIG_HOME/nix/nix.conf. # Do not edit it! extra-experimental-features = repl-flake pipe-operator lix-custom-sub-commands extra-plugin-files = /Users/ianchamberlain/.config/nix/plugins repl-overlays = /Users/ianchamberlain/.config/nix/repl-overlays.nix ``` ### Lix-module I am using the `lix-module.overlays.default` with `nix-darwin` plus a small custom overlay to disable some tests that kept failing: ```nix (final: prev: { lix = prev.lix.override { aws-sdk-cpp = prev.aws-sdk-cpp.overrideAttrs (old: { cmakeFlags = [ "-DENABLE_TESTING=OFF" ] ++ old.cmakeFlags or [ ]; }); }; }) ``` ### Lix flake inputs ``` ├───lix: git+https://git.lix.systems/lix-project/lix.git?ref=main&rev=2a336813ad2a4d64d027830507276da32927d215 │ Last modified: 2025-03-16 18:57:11 ├───lix-module: https://git.lix.systems/api/v1/repos/lix-project/nixos-module/archive/621aae0f3cceaffa6d73a4fb0f89c08d338d729e.tar.gz?narHash=sha256-NG3IRvRs3u3btVCN861FqHvgOwqcNT/Oy6PBG86F5/E%3D&rev=621aae0f3cceaffa6d73a4fb0f89c08d338d729e │ Last modified: 2025-01-29 13:54:00 ``` ### lldb backtrace ``` (lldb) bt * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=2, address=0x1015378d0) * frame #0: 0x00000001015378d0 libc++abi.1.dylib`vtable for __cxxabiv1::__si_class_type_info + 16 frame #1: 0x0000000100decc08 liblixutil.dylib`nix::MultiCommand::toJSON() + 216 frame #2: 0x00000001000be368 nix`nix::NixArgs::dumpCli() + 108 frame #3: 0x00000001000bf1a0 nix`nix::showHelp(nix::AsyncIoRoot&, std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>>>, nix::NixArgs&) + 1220 frame #4: 0x00000001000ba398 nix`nix::mainWrapped(nix::AsyncIoRoot&, int, char**) + 6452 frame #5: 0x00000001000c4060 nix`std::__1::__function::__func<main::$_0, std::__1::allocator<main::$_0>, void ()>::operator()() + 120 frame #6: 0x000000010085c148 liblixmain.dylib`nix::handleExceptions(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>> const&, std::__1::function<void ()>) + 392 frame #7: 0x00000001000c06a0 nix`main + 216 frame #8: 0x0000000187c2f154 dyld`start + 2476 ``` ### Strange behavior To check if it was just an old version bug, I tried running a new Lix version to see if its `--help` worked, and it did, but somehow this also seems to have resolved my original issue??? 1. Ran version` 2.93.0-dev-pre20250401-5a7e9e1` with `--help` (it works) 2. Ran version `2.93.0-dev-pre20250316-2a33681` with `--help` (previously failing, now working) This seems very odd to me and I can't be sure what's happening, but it suggests maybe this issue is not actually as reproducible as I first thought... also perhaps upgrading will resolve it in the general case so maybe there's nothing really to do here.