rust: irq: pass RegistrationInner as cookie to request_irq

Overview

In the Linux kernel, the following vulnerability has been resolved:

rust: irq: pass RegistrationInner as cookie to request_irq

With commit ba268514ea14 ("rust: devres: fix race condition due to nesting"), Devres::new() returns Result<Self> by value instead of initializing in-place via PinInit. Because request_irq() is called inside Devres::new(), registration.inner is still uninitialized when the IRQ is enabled, so accessing registration.inner.device() in the IRQ callback can read uninitialized memory.

Fix this by storing the Device and handler pointer in RegistrationInner and passing RegistrationInner as the IRQ cookie after its fields are initialized.

This is not needed in mainline because commit 98c63ce4d760 ("rust: irq: make Registration compatible with lifetime-bound drivers") removed Devres from irq::Registration and moved request_irq() after all fields are initialized.

Affected

• Linux >= 29e16fcd67ee5b1d0417a657294cf96fdf2f8df9 < 9a7931e847f338a687e96cde9f37e0cff83ddd84
• Linux 6.18

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.