linux-kernel - [PATCH 3.16.y-ckt 020/128] perf: Fix PERF_EVENT_IOC

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: <1453672883-2708-21-git-send-email-luis.henriques@canonical.com>
Date:	Sun, 24 Jan 2016 21:59:35 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Alexander Potapenko <glider@...gle.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Jiri Olsa <jolsa@...hat.com>,
	Kostya Serebryany <kcc@...gle.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Sasha Levin <sasha.levin@...cle.com>,
	Stephane Eranian <eranian@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Vince Weaver <vincent.weaver@...ne.edu>,
	Ingo Molnar <mingo@...nel.org>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 020/128] perf: Fix PERF_EVENT_IOC_PERIOD deadlock

3.16.7-ckt23 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Peter Zijlstra <peterz@...radead.org>

commit 642c2d671ceff40e9453203ea0c66e991e11e249 upstream.

Dmitry reported a fairly silly recursive lock deadlock for
PERF_EVENT_IOC_PERIOD, fix this by explicitly doing the inactive part of
__perf_event_period() instead of calling that function.

Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Alexander Potapenko <glider@...gle.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Kostya Serebryany <kcc@...gle.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Sasha Levin <sasha.levin@...cle.com>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Vince Weaver <vincent.weaver@...ne.edu>
Fixes: c7999c6f3fed ("perf: Fix PERF_EVENT_IOC_PERIOD migration race")
Link: http://lkml.kernel.org/r/20151130115615.GJ17308@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 kernel/events/core.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 259b9fdb6ba4..db2f2cfb58e3 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3692,7 +3692,14 @@ retry:
 		goto retry;
 	}
 
-	__perf_event_period(&pe);
+	if (event->attr.freq) {
+		event->attr.sample_freq = value;
+	} else {
+		event->attr.sample_period = value;
+		event->hw.sample_period = value;
+	}
+
+	local64_set(&event->hw.period_left, 0);
 	raw_spin_unlock_irq(&ctx->lock);
 
 	return 0;