linux-kernel - [PATCH 1/4] locking/spinlock/debug: Fix data-race in do_raw_write

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: <20250919091241.32138-2-boqun.feng@gmail.com>
Date: Fri, 19 Sep 2025 11:12:38 +0200
From: Boqun Feng <boqun.feng@...il.com>
To: "Peter Zijlstra" <peterz@...adead.org>,
	"Ingo Molnar" <mingo@...nel.org>,
	"Thomas Gleixner" <tglx@...utronix.de>
Cc: rust-for-linux@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	lkmm@...ts.linux.dev,
	"Will Deacon" <will@...nel.org>,
	"Peter Zijlstra" <peterz@...radead.org>,
	Waiman Long <longman@...hat.com>,
	"Miguel Ojeda" <ojeda@...nel.org>,
	alex.gaynor@...il.com,
	"Gary Guo" <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	"Benno Lossin" <lossin@...nel.org>,
	"Alice Ryhl" <aliceryhl@...gle.com>,
	"Trevor Gross" <tmgross@...ch.edu>,
	"Danilo Krummrich" <dakr@...nel.org>,
	"Andreas Hindborg" <a.hindborg@...nel.org>,
	Alexander Sverdlin <alexander.sverdlin@...mens.com>,
	stable@...r.kernel.org,
	Adrian Freihofer <adrian.freihofer@...mens.com>,
	"Paul E. McKenney" <paulmck@...nel.org>,
	Boqun Feng <boqun.feng@...il.com>
Subject: [PATCH 1/4] locking/spinlock/debug: Fix data-race in do_raw_write_lock

From: Alexander Sverdlin <alexander.sverdlin@...mens.com>

KCSAN reports:

BUG: KCSAN: data-race in do_raw_write_lock / do_raw_write_lock

write (marked) to 0xffff800009cf504c of 4 bytes by task 1102 on cpu 1:
 do_raw_write_lock+0x120/0x204
 _raw_write_lock_irq
 do_exit
 call_usermodehelper_exec_async
 ret_from_fork

read to 0xffff800009cf504c of 4 bytes by task 1103 on cpu 0:
 do_raw_write_lock+0x88/0x204
 _raw_write_lock_irq
 do_exit
 call_usermodehelper_exec_async
 ret_from_fork

value changed: 0xffffffff -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1103 Comm: kworker/u4:1 6.1.111

Commit 1a365e822372 ("locking/spinlock/debug: Fix various data races") has
adressed most of these races, but seems to be not consistent/not complete.

>From do_raw_write_lock() only debug_write_lock_after() part has been
converted to WRITE_ONCE(), but not debug_write_lock_before() part.
Do it now.

Cc: stable@...r.kernel.org
Fixes: 1a365e822372 ("locking/spinlock/debug: Fix various data races")
Reported-by: Adrian Freihofer <adrian.freihofer@...mens.com>
Acked-by: Waiman Long <longman@...hat.com>
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@...mens.com>
Reviewed-by: Paul E. McKenney <paulmck@...nel.org>
Signed-off-by: Boqun Feng <boqun.feng@...il.com>
---

Notes:
    SubmissionLink: https://lore.kernel.org/all/20250826102731.52507-1-alexander.sverdlin@siemens.com/

 kernel/locking/spinlock_debug.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/spinlock_debug.c b/kernel/locking/spinlock_debug.c
index 87b03d2e41db..2338b3adfb55 100644
--- a/kernel/locking/spinlock_debug.c
+++ b/kernel/locking/spinlock_debug.c
@@ -184,8 +184,8 @@ void do_raw_read_unlock(rwlock_t *lock)
 static inline void debug_write_lock_before(rwlock_t *lock)
 {
 	RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
-	RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
-	RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
+	RWLOCK_BUG_ON(READ_ONCE(lock->owner) == current, lock, "recursion");
+	RWLOCK_BUG_ON(READ_ONCE(lock->owner_cpu) == raw_smp_processor_id(),
 							lock, "cpu recursion");
 }
 
-- 
2.51.0