[PATCH] rust: security: replace `core::mem::zeroed` with `pin_init::zeroed`

From: Benno Lossin <lossin@kernel.org>

All types in `bindings` implement `Zeroable` if they can, so use
`pin_init::zeroed` instead of relying on `unsafe` code.

If this ends up not compiling in the future, something in bindgen or on
the C side changed and is most likely incorrect.

Link: https://lore.kernel.org/r/20250814093046.2071971-8-lossin@kernel.org (local)
Link: https://github.com/Rust-for-Linux/linux/issues/1189
Signed-off-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Nils Lehnen <redacted>
---
Resend of Benno's patch from the Zeroable series [1]: only patches 1, 2
and 11 of that series were applied, and the issue [2] asks for the rest
to be re-sent. Rebased onto rust-next; it applied cleanly, and a
defconfig build with CONFIG_RUST=y and CONFIG_SECURITY=y passes.

Two equivalent one-off patches were posted earlier [3][4]; Miguel asked
in [5] for a resend that keeps Benno's authorship, which this is.
Cc'ing the LSM list per Paul's request on the original thread.

[1] https://lore.kernel.org/r/20250814093046.2071971-1-lossin@kernel.org (local)
[2] https://github.com/Rust-for-Linux/linux/issues/1189
[3] https://lore.kernel.org/r/20251129135657.36144-1-atharvd440@gmail.com (local)
[4] https://lore.kernel.org/r/20260120083824.477339-8-sunke@kylinos.cn (local)
[5] https://lore.kernel.org/r/CANiq72nJqFOR9vhPBfZUNrxU+M1HMV6wN9bN6i8e9rf_oOD2qw@mail.gmail.com (local)

 rust/kernel/security.rs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/rust/kernel/security.rs b/rust/kernel/security.rs
index 9d271695265f..4dc3eba6ce84 100644
--- a/rust/kernel/security.rs
+++ b/rust/kernel/security.rs

@@ -62,8 +62,7 @@ impl SecurityCtx {
     /// Get the security context given its id.
     #[inline]
     pub fn from_secid(secid: u32) -> Result<Self> {
-        // SAFETY: `struct lsm_context` can be initialized to all zeros.
-        let mut ctx: bindings::lsm_context = unsafe { core::mem::zeroed() };
+        let mut ctx: bindings::lsm_context = pin_init::zeroed();
 
         // SAFETY: Just a C FFI call. The pointer is valid for writes.
         to_result(unsafe { bindings::security_secid_to_secctx(secid, &mut ctx) })?;

base-commit: 73e3f0710014fe6d4ed98cfc02292f6121db7558
-- 
2.43.0