linux-kernel - [PATCH 3.10 39/64] ALSA: timer: Fix leftover link at closing

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: <20160214222222.494546024@linuxfoundation.org>
Date:	Sun, 14 Feb 2016 14:23:11 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Dmitry Vyukov <dvyukov@...gle.com>,
	Takashi Iwai <tiwai@...e.de>
Subject: [PATCH 3.10 39/64] ALSA: timer: Fix leftover link at closing

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

------------------

From: Takashi Iwai <tiwai@...e.de>

commit 094fd3be87b0f102589e2d5c3fa5d06b7e20496d upstream.

In ALSA timer core, the active timer instance is managed in
active_list linked list.  Each element is added / removed dynamically
at timer start, stop and in timer interrupt.  The problem is that
snd_timer_interrupt() has a thinko and leaves the element in
active_list when it's the last opened element.  This eventually leads
to list corruption or use-after-free error.

This hasn't been revealed because we used to delete the list forcibly
in snd_timer_stop() in the past.  However, the recent fix avoids the
double-stop behavior (in commit [f784beb75ce8: ALSA: timer: Fix link
corruption due to double start or stop]), and this leak hits reality.

This patch fixes the link management in snd_timer_interrupt().  Now it
simply unlinks no matter which stream is.

BugLink: http://lkml.kernel.org/r/CACT4Y+Yy2aukHP-EDp8-ziNqNNmb-NTf=jDWXMP7jB8HDa2vng@mail.gmail.com
Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 sound/core/timer.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -696,8 +696,8 @@ void snd_timer_interrupt(struct snd_time
 			ti->cticks = ti->ticks;
 		} else {
 			ti->flags &= ~SNDRV_TIMER_IFLG_RUNNING;
-			if (--timer->running)
-				list_del_init(&ti->active_list);
+			--timer->running;
+			list_del_init(&ti->active_list);
 		}
 		if ((timer->hw.flags & SNDRV_TIMER_HW_TASKLET) ||
 		    (ti->flags & SNDRV_TIMER_IFLG_FAST))