Claude review: drm/dumb-buffer: Drop buffer-size limits for now

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

Patch Review

**Correctness: Good**

The removed check was:
```c
-	if (args->width >= 8192 || args->height >= 8192 || args->bpp > 32)
-		return -EINVAL;
```

This was problematic for two reasons:

1. **The `bpp > 32` check contradicts `drm_mode_size_dumb()`**, which explicitly supports `case 64:` (for `XRGB16161616F` and friends) at line 176 of the current tree. Any driver using `drm_mode_size_dumb()` for 64bpp formats would have the request rejected before reaching the helper.

2. **The `width >= 8192` check is too restrictive** — 8K displays are 7680x4320, which barely passes, but any buffer slightly wider than the display (e.g., with stride alignment padding) would be rejected. The `>=` rather than `>` means even exactly 8192 fails.

**Remaining overflow protection is adequate.** The existing checks that remain:

```c
if (args->bpp > U32_MAX - 8)        // prevents DIV_ROUND_UP overflow
    return -EINVAL;
cpp = DIV_ROUND_UP(args->bpp, 8);
if (cpp > U32_MAX / args->width)     // prevents pitch overflow
    return -EINVAL;
stride = cpp * args->width;
if (args->height > U32_MAX / stride) // prevents size overflow
    return -EINVAL;
size = args->height * stride;
if (PAGE_ALIGN(size) == 0)           // prevents wrap-around
    return -EINVAL;
```

These four checks form a complete chain that prevents every 32-bit arithmetic overflow in the computation path. The hard size limits were belt-and-suspenders but broke real users.

**Downstream driver concern acknowledged.** The commit message correctly notes that drivers not yet using `drm_mode_size_dumb()` should be updated. Those drivers do their own alignment math in their `dumb_create` callbacks and may still be individually vulnerable to overflow, but that's a pre-existing issue not introduced by this patch.

**Minor nit — tag ordering.** The `Fixes:` tag appears after `Signed-off-by:`, which is unconventional. Kernel convention typically places `Fixes:` before `Signed-off-by:` in the trailer block:

```
Fixes: 5ab62dd3687b ("drm: prevent integer overflows in dumb buffer creation helpers")
Reported-by: Jani Nikula <jani.nikula@linux.intel.com>
Closes: https://lore.kernel.org/dri-devel/...
Cc: ...
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
```

This is cosmetic and doesn't affect tooling, but worth fixing if a v2 is sent for other reasons.

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Generated by Claude Code Patch Reviewer