linux-kernel - [PATCH 5.16 0757/1017] rcu: Mark writes to the rcu

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: <20220405070416.729358398@linuxfoundation.org>
Date:   Tue,  5 Apr 2022 09:27:50 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Zhouyi Zhou <zhouzhouyi@...il.com>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.16 0757/1017] rcu: Mark writes to the rcu_segcblist structures ->flags field

From: Paul E. McKenney <paulmck@...nel.org>

[ Upstream commit c09929031018913b5783872a8b8cdddef4a543c7 ]

KCSAN reports data races between the rcu_segcblist_clear_flags() and
rcu_segcblist_set_flags() functions, though misreporting the latter
as a call to rcu_segcblist_is_enabled() from call_rcu().  This commit
converts the updates of this field to WRITE_ONCE(), relying on the
resulting unmarked reads to continue to detect buggy concurrent writes
to this field.

Reported-by: Zhouyi Zhou <zhouzhouyi@...il.com>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
Cc: Frederic Weisbecker <frederic@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/rcu/rcu_segcblist.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h
index 9a19328ff251..5d405943823e 100644
--- a/kernel/rcu/rcu_segcblist.h
+++ b/kernel/rcu/rcu_segcblist.h
@@ -56,13 +56,13 @@ static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp)
 static inline void rcu_segcblist_set_flags(struct rcu_segcblist *rsclp,
 					   int flags)
 {
-	rsclp->flags |= flags;
+	WRITE_ONCE(rsclp->flags, rsclp->flags | flags);
 }
 
 static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
 					     int flags)
 {
-	rsclp->flags &= ~flags;
+	WRITE_ONCE(rsclp->flags, rsclp->flags & ~flags);
 }
 
 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
-- 
2.34.1