FAILED: patch "[PATCH] rust: bug: pass TAINT_WARN to warn_slowpath_fmt() on UML" failed to apply to 6.18-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x 951d09ca450ca76a695016ea76c3fa653bd20439
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026110447-anything-wildcard-f4e0@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 951d09ca450ca76a695016ea76c3fa653bd20439 Mon Sep 17 00:00:00 2001
From: FUJITA Tomonori <fujita.tomonori@gmail.com>
Date: Thu, 1 Oct 2026 21:31:03 +0900
Subject: [PATCH] rust: bug: pass TAINT_WARN to warn_slowpath_fmt() on UML

On UML, `warn_flags!` calls `warn_slowpath_fmt()` directly. Its third
argument is a taint number, but `warn_on!` passes its bug flags there.

As a result, `add_taint()` gets 2304 instead of 9 (`TAINT_WARN`). The
warning is not recorded: `/proc/sys/kernel/tainted` stays 0 after
`warn_on!` fires, where it should be 512. It also causes an
out-of-bounds write in `add_taint()`.

Pass `TAINT_WARN` directly, as C does on UML.

Cc: stable@vger.kernel.org
Fixes: dff64b072708 ("rust: Add warn_on macro")
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Link: https://patch.msgid.link/20261001123103.2198104-1-tomo@flapping.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

diff --git a/rust/kernel/bug.rs b/rust/kernel/bug.rs
index 3566f0234ca4..af8eba4563de 100644
--- a/rust/kernel/bug.rs
+++ b/rust/kernel/bug.rs
@@ -85,6 +85,7 @@ macro_rules! warn_flags {
     ($file:expr, $flags:expr) => {
         if false {
             _ = $file;
+            _ = $flags;
         }
 
         // SAFETY: It is always safe to call `warn_slowpath_fmt()`
@@ -93,7 +94,7 @@ macro_rules! warn_flags {
             $crate::bindings::warn_slowpath_fmt(
                 $crate::str::CStrExt::as_char_ptr($crate::c_str!(::core::file!())),
                 line!() as $crate::ffi::c_int,
-                $flags as $crate::ffi::c_uint,
+                $crate::bindings::TAINT_WARN,
                 ::core::ptr::null(),
             );
         }