linux-kernel - [for-next][PATCH 1/2] jump_label: rust: pass a mut ptr to `static_key

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241121021257.192412005@goodmis.org>
Date: Wed, 20 Nov 2024 21:12:27 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 kernel test robot <lkp@...el.com>,
 Alice Ryhl <aliceryhl@...gle.com>,
 Miguel Ojeda <ojeda@...nel.org>
Subject: [for-next][PATCH 1/2] jump_label: rust: pass a mut ptr to `static_key_count`

From: Alice Ryhl <aliceryhl@...gle.com>

When building the rust_print sample with CONFIG_JUMP_LABEL=n, the Rust
static key support falls back to using static_key_count. This function
accepts a mutable pointer to the `struct static_key`, but the Rust
abstractions are incorrectly passing a const pointer.

This means that builds using CONFIG_JUMP_LABEL=n and SAMPLE_RUST_PRINT=y
fail with the following error message:

	error[E0308]: mismatched types
	  --> <root>/samples/rust/rust_print_main.rs:87:5
	   |
	87 | /     kernel::declare_trace! {
	88 | |         /// # Safety
	89 | |         ///
	90 | |         /// Always safe to call.
	91 | |         unsafe fn rust_sample_loaded(magic: c_int);
	92 | |     }
	   | |     ^
	   | |     |
	   | |_____types differ in mutability
	   |       arguments to this function are incorrect
	   |
	   = note: expected raw pointer `*mut kernel::bindings::static_key`
	              found raw pointer `*const kernel::bindings::static_key`
	note: function defined here
	  --> <root>/rust/bindings/bindings_helpers_generated.rs:33:12
	   |
	33 |     pub fn static_key_count(key: *mut static_key) -> c_int;
	   |            ^^^^^^^^^^^^^^^^

To fix this, insert a pointer cast so that the pointer is mutable.

Link: https://lore.kernel.org/20241118202727.73646-1-aliceryhl@google.com
Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202411181440.qEdcuyh6-lkp@intel.com/
Fixes: 169484ab6677 ("rust: add arch_static_branch")
Signed-off-by: Alice Ryhl <aliceryhl@...gle.com>
Acked-by: Miguel Ojeda <ojeda@...nel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 rust/kernel/jump_label.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/kernel/jump_label.rs b/rust/kernel/jump_label.rs
index 2f2df03a3275..b5aff632ecc7 100644
--- a/rust/kernel/jump_label.rs
+++ b/rust/kernel/jump_label.rs
@@ -26,7 +26,7 @@ macro_rules! static_branch_unlikely {
 
         #[cfg(not(CONFIG_JUMP_LABEL))]
         {
-            $crate::bindings::static_key_count(_key) > 0
+            $crate::bindings::static_key_count(_key.cast_mut()) > 0
         }
 
         #[cfg(CONFIG_JUMP_LABEL)]
-- 
2.45.2