Re: [PATCH v5 01/19] rust: drm: ioctl: fix unbounded lifetimes in ioctl handler arguments

On Sun Jun 28, 2026 at 11:53 PM JST, Danilo Krummrich wrote:
> References to dev, data, and file in the declare_drm_ioctls! macro are
> created via unsafe pointer dereferences, producing unbounded lifetimes.
> If an ioctl handler explicitly annotates its parameters with 'static,
> the compiler accepts this, allowing the handler to stash references that
> outlive the ioctl call.
>
> Fix this by adding a higher-ranked function pointer coercion that
> enforces the handler accepts universally quantified lifetimes:
>
>   let _: for<'a> fn(&'a _, &'a mut _, &'a _) -> _ = $func;
>
> Since the handler must be coercible to a function pointer accepting any
> lifetime 'a, it can no longer demand 'static on any parameter.
>
> Cc: [email protected]
> Fixes: 9a69570682b1 ("rust: drm: ioctl: Add DRM ioctl abstraction")
> Reported-by: [email protected]
> Closes: https://lore.kernel.org/all/[email protected]/
> Suggested-by: Gary Guo <[email protected]>
> Signed-off-by: Danilo Krummrich <[email protected]>

Reviewed-by: Alexandre Courbot <[email protected]>