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SIGILL in arithmetic code #445

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opened 2024-07-12 03:59:35 +00:00 by xddxdd · 4 comments

xddxdd commented

2024-07-12 03:59:35 +00:00

Describe the bug

Lix crashes with SIGILL when evaluating certain expressions.

dmesg message:

[ 3503.611074] traps: nix-instantiate[526663] trap invalid opcode ip:7f97ea75cf28 sp:7ffc002d3c30 error:0 in liblixexpr.so[7f97ea687000+1b5000]

Coredump stack trace: https://pb.ltn.pw/M9ivd3mz

Steps To Reproduce

Download https://gist.github.com/duairc/5c9bb3c922e5d501a1edb9e7b3b845ba to net.nix
Run nix-instantiate --eval -E 'with import <nixpkgs> { }; let net = callPackage ./net.nix {}; in net.lib.net.cidr.host 123 "fe80::/10"'

Expected behavior

It should evaluate instead of crashing. Evaluation result on Nix 2.18.4: "fe80::7b"

`nix --version` output

nix (Lix, like Nix) 2.90.0

Additional context

Add any other context about the problem here.

## Describe the bug Lix crashes with SIGILL when evaluating certain expressions. dmesg message: ``` [ 3503.611074] traps: nix-instantiate[526663] trap invalid opcode ip:7f97ea75cf28 sp:7ffc002d3c30 error:0 in liblixexpr.so[7f97ea687000+1b5000] ``` Coredump stack trace: https://pb.ltn.pw/M9ivd3mz ## Steps To Reproduce 1. Download https://gist.github.com/duairc/5c9bb3c922e5d501a1edb9e7b3b845ba to `net.nix` 2. Run `nix-instantiate --eval -E 'with import <nixpkgs> { }; let net = callPackage ./net.nix {}; in net.lib.net.cidr.host 123 "fe80::/10"'` ## Expected behavior It should evaluate instead of crashing. Evaluation result on Nix 2.18.4: `"fe80::7b"` ## `nix --version` output ``` nix (Lix, like Nix) 2.90.0 ``` ## Additional context Add any other context about the problem here.

xddxdd added the

bug

label

2024-07-12 03:59:35 +00:00

jade commented

2024-07-12 09:41:53 +00:00

Owner

duplicate of this, but, wtf, nixpkgs should not be relying on overflow semantics, especially given our integers are signed.

#423

@janik i believe this is your code

duplicate of this, but, *wtf*, nixpkgs should *not* be relying on overflow semantics, especially given our integers are signed. https://git.lix.systems/lix-project/lix/issues/423 @janik i believe this is your code

janik commented

2024-07-12 09:46:22 +00:00

Member

Hey, I have been working on lib.network which should be unrelated https://github.com/NixOS/nixpkgs/pull/318712

The issue above is talking about a gist, that isn't related to nixpkgs afaict, in nixpkgs we are using a toml parsing hack to convert from base10 to base16.

Hey, I have been working on `lib.network` which should be unrelated https://github.com/NixOS/nixpkgs/pull/318712 The issue above is talking about a gist, that isn't related to nixpkgs afaict, in nixpkgs we are using a toml parsing hack to convert from base10 to base16.

jade commented

2024-07-12 11:21:06 +00:00

Owner

anyway. we're closing this as duplicate and we would additionally argue that the code doing the overflow is broken, itself, because stuff overflowing an i64 is itself not usually a sign of correctness.

the nixpkgs lib stuff that janik wrote may be a suitable replacement for this gist.

jade

2024-07-12 11:21:19 +00:00

closed this issue
added the
Status
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label

lix-bot commented

2024-07-12 16:22:43 +00:00

Member

This issue was mentioned on Gerrit on the following CLs:

commit message in cl/1596 ("language: cleanly ban integer overflows")

This issue was mentioned on Gerrit on the following CLs: * commit message in [cl/1596](https://gerrit.lix.systems/c/lix/+/1596) ("language: cleanly ban integer overflows")