[PATCH] rust: devres: add 'static bound to Devres<T>

[Danilo Krummrich <dakr@kernel.org>]

Devres::new() registers a callback with the C devres subsystem via
devres_node_add(). If the Devres is leaked (e.g. via
core::mem::forget(), which is safe), its Drop impl never runs, and the
devres release callback will revoke the inner Revocable on device
unbind, which drops T in place. If T contains non-'static references,
those may be dangling by that point.

Add a 'static bound to prevent storing types with borrowed data in
Devres.

Fixes: 76c01ded724b ("rust: add devres abstraction")
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/devres.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs
index 9e5f93aed20c..2e258d31a45c 100644
--- a/rust/kernel/devres.rs
+++ b/rust/kernel/devres.rs
@@ -122,7 +122,7 @@ struct Inner<T> {
 /// # Ok(())
 /// # }
 /// ```
-pub struct Devres<T: Send> {
+pub struct Devres<T: Send + 'static> {
     dev: ARef<Device>,
     inner: Arc<Inner<T>>,
 }
@@ -184,7 +184,7 @@ pub(super) unsafe fn devres_node_remove(
     }
 }
 
-impl<T: Send> Devres<T> {
+impl<T: Send + 'static> Devres<T> {
     /// Creates a new [`Devres`] instance of the given `data`.
     ///
     /// The `data` encapsulated within the returned `Devres` instance' `data` will be
@@ -349,7 +349,7 @@ unsafe impl<T: Send> Send for Devres<T> {}
 // SAFETY: `Devres` can be shared with any task, if `T: Sync`.
 unsafe impl<T: Send + Sync> Sync for Devres<T> {}
 
-impl<T: Send> Drop for Devres<T> {
+impl<T: Send + 'static> Drop for Devres<T> {
     fn drop(&mut self) {
         // SAFETY: When `drop` runs, it is guaranteed that nobody is accessing the revocable data
         // anymore, hence it is safe not to wait for the grace period to finish.

base-commit: 56785dcb2ef6d3cff82ac33f2e34db94377416a3
-- 
2.54.0