Nixpkgs version

• Unstable (25.11)

Describe the bug

Firefox 144.0 from nixpkgs (firefox-unwrapped) consistently crashes right after a page finishes loading whenever favicons are enabled. The crash signature is:

[@ nsPNGEncoder::ConvertHostARGBRow ]

The stack shows the favicon pipeline:
nsFaviconService::SetFaviconForPage → OptimizeIconSizes → imgTools::EncodeScaledImage("image/png") → nsPNGEncoder::ConvertHostARGBRow.

Disabling site icons avoids the crash entirely.

Update:

there are still other crashes occurring for me even after applying workarounds.

Steps to reproduce

1. Install firefox-unwrapped 144.0 from nixpkgs on macOS arm64.
2. Ensure about:config → browser.chrome.site_icons = true (default).
3. Launch Firefox, visit any website (e.g., docs.mozilla.org, example.com).
4. As the page fully loads, Firefox crashes within ~15–30s of uptime.

Expected behavior

No crash and page loads and favicon is processed normally.

Actual behavior

Parent process segfaults with EXC_BAD_ACCESS / KERN_INVALID_ADDRESS in the PNG encoder while encoding/scaling the favicon.

Crash reports (Socorro Crash IDs)

• 876cd736-0712-4f31-8ac5-d2a230251018 (2025-10-18 23:59:54 UTC, uptime 15s)
• 467bb7a1-938b-403f-99db-2a5880251018 (2025-10-18 23:48:52 UTC, uptime 28s)
• 56439d74-541a-4318-9e23-8d75e0251018 (2025-10-18 18:59:16 UTC, uptime 19s)

All show the same path into nsPNGEncoder::ConvertHostARGBRow via the favicon service.

What I’ve tried

• Workaround: about:config → browser.chrome.site_icons=false → no more crashes.
• Cleared favicon cache: deleted favicons.sqlite (+ -wal/-shm) from profile → crashes return once icons are re-enabled.
• firefox-bin-unwrapped still has the same crash
• “Startup cache” cleared from about:support → no change.
• Comparison: Installing official/Homebrew Firefox does not crash under the same profile and sites.

System metadata

• system: "aarch64-darwin"
• host os: Darwin 25.0.0, macOS 26.0.1
• multi-user?: yes
• sandbox: no
• version: nix-env (Determinate Nix 3.11.2) 2.31.1
• nixpkgs: /nix/store/b1hmqq7kiy26q08663w45mm6wlrx1nn1-source

Are you using nix-darwin?

Yes, I am using nix-darwin on my system but this package is installed on nix home manager.

Notify maintainers

@lovesegfault
@Hexa

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