[PATCH RFC v3 05/15] rust: drm: fix missing owner in file_operations

[Kari Argillander <kari.argillander@gmail.com>]

Fix missing .owner field in file_operations. This has been previosly
left out because Rust feature `const_refs_to_static` has not been
enabled. Now that it is we can make define owner even in const context.

This should probably fix use-after-free problems in situations where
file is opened and module driver is unloaded during that.

Signed-off-by: Kari Argillander <kari.argillander@gmail.com>
---
 drivers/gpu/drm/nova/driver.rs | 2 ++
 drivers/gpu/drm/tyr/driver.rs  | 2 ++
 rust/kernel/drm/device.rs      | 2 +-
 rust/kernel/drm/driver.rs      | 4 ++++
 rust/kernel/drm/gem/mod.rs     | 5 +++--
 5 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/nova/driver.rs b/drivers/gpu/drm/nova/driver.rs
index b1af0a099551..7ce505802716 100644
--- a/drivers/gpu/drm/nova/driver.rs
+++ b/drivers/gpu/drm/nova/driver.rs
@@ -14,6 +14,7 @@
 
 use crate::file::File;
 use crate::gem::NovaObject;
+use crate::THIS_MODULE;
 
 pub(crate) struct NovaDriver {
     #[expect(unused)]
@@ -65,6 +66,7 @@ fn probe(adev: &auxiliary::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<S
 
 #[vtable]
 impl drm::Driver for NovaDriver {
+    type ThisModule = THIS_MODULE;
     type Data = NovaData;
     type File = File;
     type Object = gem::Object<NovaObject>;
diff --git a/drivers/gpu/drm/tyr/driver.rs b/drivers/gpu/drm/tyr/driver.rs
index f0da58932702..11932d3f03ff 100644
--- a/drivers/gpu/drm/tyr/driver.rs
+++ b/drivers/gpu/drm/tyr/driver.rs
@@ -25,6 +25,7 @@
 use crate::gpu;
 use crate::gpu::GpuInfo;
 use crate::regs;
+use crate::THIS_MODULE;
 
 pub(crate) type IoMem = kernel::io::mem::IoMem<SZ_2M>;
 
@@ -179,6 +180,7 @@ fn drop(self: Pin<&mut Self>) {
 
 #[vtable]
 impl drm::Driver for TyrDriver {
+    type ThisModule = THIS_MODULE;
     type Data = TyrData;
     type File = File;
     type Object = drm::gem::Object<TyrObject>;
diff --git a/rust/kernel/drm/device.rs b/rust/kernel/drm/device.rs
index 3ce8f62a0056..a740c87933d0 100644
--- a/rust/kernel/drm/device.rs
+++ b/rust/kernel/drm/device.rs
@@ -92,7 +92,7 @@ impl<T: drm::Driver> Device<T> {
         fops: &Self::GEM_FOPS,
     };
 
-    const GEM_FOPS: bindings::file_operations = drm::gem::create_fops();
+    const GEM_FOPS: bindings::file_operations = drm::gem::create_fops::<T::ThisModule>();
 
     /// Create a new `drm::Device` for a `drm::Driver`.
     pub fn new(dev: &device::Device, data: impl PinInit<T::Data, Error>) -> Result<ARef<Self>> {
diff --git a/rust/kernel/drm/driver.rs b/rust/kernel/drm/driver.rs
index f30ee4c6245c..a157db2ea02b 100644
--- a/rust/kernel/drm/driver.rs
+++ b/rust/kernel/drm/driver.rs
@@ -9,6 +9,7 @@
     error::{to_result, Result},
     prelude::*,
     sync::aref::ARef,
+    this_module::ThisModule,
 };
 use macros::vtable;
 
@@ -99,6 +100,9 @@ pub trait AllocImpl: super::private::Sealed + drm::gem::IntoGEMObject {
 /// drm_driver` to be registered in the DRM subsystem.
 #[vtable]
 pub trait Driver {
+    /// Module ownership for this device, provided via `THIS_MODULE`.
+    type ThisModule: ThisModule;
+
     /// Context data associated with the DRM driver
     type Data: Sync + Send;
 
diff --git a/rust/kernel/drm/gem/mod.rs b/rust/kernel/drm/gem/mod.rs
index d49a9ba02635..705afea65ff6 100644
--- a/rust/kernel/drm/gem/mod.rs
+++ b/rust/kernel/drm/gem/mod.rs
@@ -11,6 +11,7 @@
     error::{to_result, Result},
     prelude::*,
     sync::aref::{ARef, AlwaysRefCounted},
+    this_module::ThisModule,
     types::Opaque,
 };
 use core::{ops::Deref, ptr::NonNull};
@@ -292,10 +293,10 @@ impl<T: DriverObject> AllocImpl for Object<T> {
     };
 }
 
-pub(super) const fn create_fops() -> bindings::file_operations {
+pub(super) const fn create_fops<TM: ThisModule>() -> bindings::file_operations {
     let mut fops: bindings::file_operations = pin_init::zeroed();
 
-    fops.owner = core::ptr::null_mut();
+    fops.owner = TM::OWNER.as_ptr();
     fops.open = Some(bindings::drm_open);
     fops.release = Some(bindings::drm_release);
     fops.unlocked_ioctl = Some(bindings::drm_ioctl);

-- 
2.43.0