From patchwork Mon Mar 7 22:48:03 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 593678 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 740161402A8; Tue, 8 Mar 2016 10:03:19 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1ad4BH-0005IO-Rt; Mon, 07 Mar 2016 23:03:15 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1ad41S-0007tP-Jy for kernel-team@lists.ubuntu.com; Mon, 07 Mar 2016 22:53:06 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1ad41S-0000EI-69; Mon, 07 Mar 2016 22:53:06 +0000 Received: from kamal by fourier with local (Exim 4.86) (envelope-from ) id 1ad41P-0001wy-Hb; Mon, 07 Mar 2016 14:53:03 -0800 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 4.2.y-ckt 092/273] ALSA: timer: Fix leftover link at closing Date: Mon, 7 Mar 2016 14:48:03 -0800 Message-Id: <1457391064-6660-93-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1457391064-6660-1-git-send-email-kamal@canonical.com> References: <1457391064-6660-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 4.2 Cc: Takashi Iwai , Kamal Mostafa X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 4.2.8-ckt5 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Takashi Iwai 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 Signed-off-by: Takashi Iwai Signed-off-by: Kamal Mostafa --- sound/core/timer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/sound/core/timer.c b/sound/core/timer.c index a8b415d..a011b67 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -744,8 +744,8 @@ void snd_timer_interrupt(struct snd_timer * timer, unsigned long ticks_left) 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))