linux-kernel - [RFC PATCH] Cleanup: preempt notifiers: disallow hlist

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-next>] [day] [month] [year] [list]

Message-Id: <1431881590-1456-1-git-send-email-mathieu.desnoyers@efficios.com>
Date:	Sun, 17 May 2015 12:53:10 -0400
From:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:	Ingo Molnar <mingo@...hat.com>
Cc:	linux-kernel@...r.kernel.org,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Avi Kivity <avi@...ranet.com>
Subject: [RFC PATCH] Cleanup: preempt notifiers: disallow hlist_del within unsafe iteration

preempt_notifier_unregister() documents:

  "This is safe to call from within a preemption notifier."

However, both fire_sched_in_preempt_notifiers() and
fire_sched_out_preempt_notifiers() are using hlist_for_each_entry(),
which is not safe against entry removal during iteration.

Inspection of the kvm code does not reveal any use of
preempt_notifier_unregister() within the preempt notifiers.

Therefore, fix the bogus comment.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
CC: Ingo Molnar <mingo@...hat.com>
CC: Peter Zijlstra <peterz@...radead.org>
CC: Avi Kivity <avi@...ranet.com>
---
 kernel/sched/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 57bd333..9edefec 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2119,7 +2119,7 @@ EXPORT_SYMBOL_GPL(preempt_notifier_register);
  * preempt_notifier_unregister - no longer interested in preemption notifications
  * @notifier: notifier struct to unregister
  *
- * This is safe to call from within a preemption notifier.
+ * This is *not* safe to call from within a preemption notifier.
  */
 void preempt_notifier_unregister(struct preempt_notifier *notifier)
 {
-- 
2.1.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/