linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Oleg Nesterov <oleg@redhat.com>, Ingo Molnar <mingo@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	syzbot+55acd54b57bb4b3840a4@syzkaller.appspotmail.com
Subject: [patch 1/6] posix-cpu-timers: Always clear head pointer on dequeue
Date: Thu, 05 Sep 2019 14:03:40 +0200	[thread overview]
Message-ID: <20190905120539.707986830@linutronix.de> (raw)
In-Reply-To: 20190905120339.561100423@linutronix.de

The head pointer in struct cpu_timer is checked to be NULL in
posix_cpu_timer_del() when the delete raced with the exit cleanup. The
works correctly as long as the timer is actually dequeued via
posix_cpu_timers_exit*().

But if the timer was dequeued due to expiry the head pointer is still set
and triggers the warning.

In fact keeping the head pointer around after any dequeue is pointless as
is has no meaning at all after that.

Clear the head pointer always on dequeue and remove the unused requeue
function while at it.

Fixes: 60bda037f1dd ("posix-cpu-timers: Utilize timerqueue for storage")
Reported-by: syzbot+55acd54b57bb4b3840a4@syzkaller.appspotmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 include/linux/posix-timers.h |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -74,11 +74,6 @@ struct cpu_timer {
 	int			firing;
 };
 
-static inline bool cpu_timer_requeue(struct cpu_timer *ctmr)
-{
-	return timerqueue_add(ctmr->head, &ctmr->node);
-}
-
 static inline bool cpu_timer_enqueue(struct timerqueue_head *head,
 				     struct cpu_timer *ctmr)
 {
@@ -88,8 +83,10 @@ static inline bool cpu_timer_enqueue(str
 
 static inline void cpu_timer_dequeue(struct cpu_timer *ctmr)
 {
-	if (!RB_EMPTY_NODE(&ctmr->node.node))
+	if (ctmr->head) {
 		timerqueue_del(ctmr->head, &ctmr->node);
+		ctmr->head = NULL;
+	}
 }
 
 static inline u64 cpu_timer_getexpires(struct cpu_timer *ctmr)



  reply	other threads:[~2019-09-05 12:12 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-05 12:03 [patch 0/6] posix-cpu-timers: Fallout fixes and permission tightening Thomas Gleixner
2019-09-05 12:03 ` Thomas Gleixner [this message]
2019-09-05 15:49   ` [patch 1/6] posix-cpu-timers: Always clear head pointer on dequeue Frederic Weisbecker
2019-09-05 12:03 ` [patch 2/6] posix-cpu-timers: Fix permission check regression Thomas Gleixner
2019-09-05 17:31   ` Frederic Weisbecker
2019-09-05 18:55     ` Thomas Gleixner
2019-09-05 21:15       ` [patch V2 " Thomas Gleixner
2019-09-09 15:13         ` Frederic Weisbecker
2019-09-10 11:18         ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-09-05 12:03 ` [patch 3/6] posix-cpu-timers: Restrict timer_create() permissions Thomas Gleixner
2019-09-21  0:44   ` Frederic Weisbecker
2019-09-05 12:03 ` [patch 4/6] posix-cpu-timers: Restrict clock_gettime() permissions Thomas Gleixner
2019-09-23 13:39   ` Frederic Weisbecker
2019-09-05 12:03 ` [patch 5/6] posix-cpu-timers: Sanitize thread clock permissions Thomas Gleixner
2019-09-05 12:21   ` Peter Zijlstra
2019-09-05 14:11     ` Thomas Gleixner
2019-09-23 14:03   ` Frederic Weisbecker
2019-09-05 12:03 ` [patch 6/6] posix-cpu-timers: Make PID=0 and PID=self handling consistent Thomas Gleixner
2019-09-23 14:13   ` Frederic Weisbecker
2019-09-23 14:17     ` Thomas Gleixner
2019-09-05 14:48 ` [patch 0/6] posix-cpu-timers: Fallout fixes and permission tightening Frederic Weisbecker
2019-09-05 14:57   ` Thomas Gleixner
2019-09-05 15:21     ` Frederic Weisbecker
2019-09-05 20:32 ` Kees Cook
2019-09-05 21:13   ` Thomas Gleixner

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190905120539.707986830@linutronix.de \
    --to=tglx@linutronix.de \
    --cc=fweisbec@gmail.com \
    --cc=keescook@chromium.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=oleg@redhat.com \
    --cc=peterz@infradead.org \
    --cc=syzbot+55acd54b57bb4b3840a4@syzkaller.appspotmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).