linux-kernel - [PATCH 4.4 13/99] locking/lockdep: Add debug_locks check in __lock

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: <20191003154300.292791604@linuxfoundation.org>
Date:   Thu,  3 Oct 2019 17:52:36 +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,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        syzbot+53383ae265fb161ef488@...kaller.appspotmail.com,
        Waiman Long <longman@...hat.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will.deacon@....com>,
        Ingo Molnar <mingo@...nel.org>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.4 13/99] locking/lockdep: Add debug_locks check in __lock_downgrade()

From: Waiman Long <longman@...hat.com>

[ Upstream commit 513e1073d52e55b8024b4f238a48de7587c64ccf ]

Tetsuo Handa had reported he saw an incorrect "downgrading a read lock"
warning right after a previous lockdep warning. It is likely that the
previous warning turned off lock debugging causing the lockdep to have
inconsistency states leading to the lock downgrade warning.

Fix that by add a check for debug_locks at the beginning of
__lock_downgrade().

Reported-by: Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Reported-by: syzbot+53383ae265fb161ef488@...kaller.appspotmail.com
Signed-off-by: Waiman Long <longman@...hat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Will Deacon <will.deacon@....com>
Link: https://lkml.kernel.org/r/1547093005-26085-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/locking/lockdep.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index f2df5f86af28a..a419696709a1a 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3314,6 +3314,9 @@ __lock_set_class(struct lockdep_map *lock, const char *name,
 	unsigned int depth;
 	int i;
 
+	if (unlikely(!debug_locks))
+		return 0;
+
 	depth = curr->lockdep_depth;
 	/*
 	 * This function is about (re)setting the class of a held lock,
-- 
2.20.1