[PATCH] rust: firmware: avoid UB in example by passing parameter

[PATCH] rust: firmware: avoid UB in example by passing parameter

[Miguel Ojeda]

The `Firmware` example crafts an `ARef<Device>` using a null pointer,
which breaks the safety requirements of `Device::get_device()`.

Instead, pass an `ARef` via a parameter, which is simpler, avoids UB
and removes an `unsafe` block.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 rust/kernel/firmware.rs | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs
index 71168d8004e2..3aa9de3c4a04 100644
--- a/rust/kernel/firmware.rs
+++ b/rust/kernel/firmware.rs
@@ -51,12 +51,9 @@ fn request_nowarn() -> Self {
 /// # Examples
 ///
 /// ```no_run
-/// # use kernel::{device::Device, firmware::Firmware};
-///
-/// # fn no_run() -> Result<(), Error> {
-/// # // SAFETY: *NOT* safe, just for the example to get an `ARef<Device>` instance
-/// # let dev = unsafe { Device::get_device(core::ptr::null_mut()) };
+/// # use kernel::{device::Device, firmware::Firmware, sync::aref::ARef};
 ///
+/// # fn no_run(dev: ARef<Device>) -> Result<(), Error> {
 /// let fw = Firmware::request(c"path/to/firmware.bin", &dev)?;
 /// let blob = fw.data();
 ///

base-commit: 8cdeaa50eae8dad34885515f62559ee83e7e8dda
-- 
2.55.0

Re: [PATCH] rust: firmware: avoid UB in example by passing parameter

[Gary Guo]

On Sat Jul 11, 2026 at 7:02 PM BST, Miguel Ojeda wrote:
> The `Firmware` example crafts an `ARef<Device>` using a null pointer,
> which breaks the safety requirements of `Device::get_device()`.
> 
> Instead, pass an `ARef` via a parameter, which is simpler, avoids UB
> and removes an `unsafe` block.
> 
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Reviewed-by: Gary Guo <gary@garyguo.net>

> ---
>  rust/kernel/firmware.rs | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)

Re: [PATCH] rust: firmware: avoid UB in example by passing parameter

[Alexandre Courbot]

On Sun Jul 12, 2026 at 3:02 AM JST, Miguel Ojeda wrote:
> The `Firmware` example crafts an `ARef<Device>` using a null pointer,
> which breaks the safety requirements of `Device::get_device()`.
>
> Instead, pass an `ARef` via a parameter, which is simpler, avoids UB
> and removes an `unsafe` block.
>
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>

Re: [PATCH] rust: firmware: avoid UB in example by passing parameter

[Danilo Krummrich]

On Sat Jul 11, 2026 at 8:02 PM CEST, Miguel Ojeda wrote:
> diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs
> index 71168d8004e2..3aa9de3c4a04 100644
> --- a/rust/kernel/firmware.rs
> +++ b/rust/kernel/firmware.rs
> @@ -51,12 +51,9 @@ fn request_nowarn() -> Self {
>  /// # Examples
>  ///
>  /// ```no_run
> -/// # use kernel::{device::Device, firmware::Firmware};
> -///
> -/// # fn no_run() -> Result<(), Error> {
> -/// # // SAFETY: *NOT* safe, just for the example to get an `ARef<Device>` instance
> -/// # let dev = unsafe { Device::get_device(core::ptr::null_mut()) };
> +/// # use kernel::{device::Device, firmware::Firmware, sync::aref::ARef};
>  ///

We could take the chance to also drop this empty line.

> +/// # fn no_run(dev: ARef<Device>) -> Result<(), Error> {
>  /// let fw = Firmware::request(c"path/to/firmware.bin", &dev)?;
>  /// let blob = fw.data();
>  ///