[PATCH v2 1/2] rust: pwm: Fix potential memory leak on init error

[Kari Argillander]

When initializing a PWM chip using pwmchip_alloc(), the allocated device
owns an initial reference that must be released on all error paths.

If __pinned_init() were to fail, the allocated pwm_chip would currently
leak because the error path returns without calling pwmchip_put().

Fixes: 7b3dce814a15 ("rust: pwm: Add Kconfig and basic data structures")
Signed-off-by: Kari Argillander <kari.argillander@xxxxxxxxx>
---
 rust/kernel/pwm.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/rust/kernel/pwm.rs b/rust/kernel/pwm.rs
index 2dd72a39acb5..4f683158fc08 100644
--- a/rust/kernel/pwm.rs
+++ b/rust/kernel/pwm.rs
@@ -607,7 +607,11 @@ pub fn new<'a>(
         let drvdata_ptr = unsafe { bindings::pwmchip_get_drvdata(c_chip_ptr) };
 
         // SAFETY: We construct the `T` object in-place in the allocated private memory.
-        unsafe { data.__pinned_init(drvdata_ptr.cast())? };
+        unsafe { data.__pinned_init(drvdata_ptr.cast()) }.inspect_err(|_| {
+            // SAFETY: It is safe to call `pwmchip_put()` with a valid pointer obtained
+            // from `pwmchip_alloc()`. We will not use pointer after this.
+            unsafe { bindings::pwmchip_put(c_chip_ptr) }
+        })?;
 
         // SAFETY: `c_chip_ptr` points to a valid chip.
         unsafe {

-- 
2.43.0