Claude review: drm: Safe font-data access in log/panic drawing

[Claude Code Review Bot <claude-review@example.com>]

Overall Series Review

Subject: drm: Safe font-data access in log/panic drawing
Author: Thomas Zimmermann <tzimmermann@suse.de>
Patches: 10
Reviewed: 2026-06-04T16:27:41.201252

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This is a clean, well-motivated 4-patch series from Thomas Zimmermann that fixes a real correctness bug in glyph lookup. The existing `drm_draw_get_char_bitmap()` takes a signed `char c`, which means:

1. Characters with values 128–255 produce **negative offsets** in the pointer arithmetic `font->data + (c * font->height) * font_pitch`, causing out-of-bounds reads.
2. There is no bounds checking at all — any character value blindly indexes into font data.

The series introduces a proper `font_data_glyph_buf()` helper in the font-data API with bounds validation, converts both callers (`drm_log` and `drm_panic`), and removes the old unsafe inline. The approach of pushing this into `lib/fonts/` is correct — glyph lookup belongs with the font-data abstraction, not in a DRM-internal header.

The series is logically structured: new API first (patch 1), then caller conversions (patches 2–3), then dead code removal (patch 4). No issues found with correctness.

**Verdict: Looks good. No bugs found.**

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