Fix memory ownership issue in the init function

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## 0.4.2 (2024-06-17)
+
+- Fixed a memory ownership issue in `nrf_modem_init`. The `nrf_modem_init_params` pointer given to the init must
+  have a static lifetime. This has been a stack variable since forever, including in the original `nrfxlib` rust crate.  
+  Originally this seems to have not been required, but this changed +-4 years ago
+  without documentation update from Nordic.
+
 ## 0.4.1 (2023-09-22)
 
 - Added a new modem init function where the memory layout can be manually specified

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "nrf-modem"
-version = "0.4.1"
+version = "0.4.2"
 edition = "2021"
 rust-version = "1.64"
 license = "MIT OR Apache-2.0"
@@ -25,6 +25,7 @@ at-commands = "0.5.2"
 no-std-net = "0.6.0"
 critical-section = "1.1"
 embassy-sync = "0.3.0"
+grounded = "0.2.0"
 
 [features]
 default = []

src/lib.rs

@@ -113,6 +113,9 @@ pub async fn init_with_custom_layout(
     }
 
     // Tell nrf_modem what memory it can use.
+    static PARAMS: grounded::uninit::GroundedCell<nrfxlib_sys::nrf_modem_init_params> =
+        grounded::uninit::GroundedCell::uninit();
+
     let params = nrfxlib_sys::nrf_modem_init_params {
         shmem: nrfxlib_sys::nrf_modem_shmem_cfg {
             ctrl: nrfxlib_sys::nrf_modem_shmem_cfg__bindgen_ty_1 {
@@ -141,6 +144,8 @@ pub async fn init_with_custom_layout(
         fault_handler: Some(modem_fault_handler),
     };
 
+    critical_section::with(|_| unsafe { PARAMS.get().write(params) });
+
     unsafe {
         // Use the same TX memory region as above
         cortex_m::interrupt::free(|cs| {
@@ -152,7 +157,7 @@ pub async fn init_with_custom_layout(
     }
 
     // OK, let's start the library
-    unsafe { nrfxlib_sys::nrf_modem_init(&params) }.into_result()?;
+    unsafe { nrfxlib_sys::nrf_modem_init(PARAMS.get()) }.into_result()?;
 
     // Initialize AT notifications
     at_notifications::initialize()?;