From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out4-smtp.messagingengine.com ([66.111.4.28]:42415 "EHLO out4-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750730AbdFLMV6 (ORCPT ); Mon, 12 Jun 2017 08:21:58 -0400 Subject: FAILED: patch "[PATCH] ALSA: timer: Fix race between read and ioctl" failed to apply to 3.18-stable tree To: tiwai@suse.de, glider@google.com, stable@vger.kernel.org Cc: From: Date: Mon, 12 Jun 2017 14:21:52 +0200 Message-ID: <1497270112204178@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: The patch below does not apply to the 3.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >>From d11662f4f798b50d8c8743f433842c3e40fe3378 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Fri, 2 Jun 2017 15:03:38 +0200 Subject: [PATCH] ALSA: timer: Fix race between read and ioctl The read from ALSA timer device, the function snd_timer_user_tread(), may access to an uninitialized struct snd_timer_user fields when the read is concurrently performed while the ioctl like snd_timer_user_tselect() is invoked. We have already fixed the races among ioctls via a mutex, but we seem to have forgotten the race between read vs ioctl. This patch simply applies (more exactly extends the already applied range of) tu->ioctl_lock in snd_timer_user_tread() for closing the race window. Reported-by: Alexander Potapenko Tested-by: Alexander Potapenko Cc: Signed-off-by: Takashi Iwai diff --git a/sound/core/timer.c b/sound/core/timer.c index 2f836ca09860..1118bd8e2d3c 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -1959,6 +1959,7 @@ static ssize_t snd_timer_user_read(struct file *file, char __user *buffer, tu = file->private_data; unit = tu->tread ? sizeof(struct snd_timer_tread) : sizeof(struct snd_timer_read); + mutex_lock(&tu->ioctl_lock); spin_lock_irq(&tu->qlock); while ((long)count - result >= unit) { while (!tu->qused) { @@ -1974,7 +1975,9 @@ static ssize_t snd_timer_user_read(struct file *file, char __user *buffer, add_wait_queue(&tu->qchange_sleep, &wait); spin_unlock_irq(&tu->qlock); + mutex_unlock(&tu->ioctl_lock); schedule(); + mutex_lock(&tu->ioctl_lock); spin_lock_irq(&tu->qlock); remove_wait_queue(&tu->qchange_sleep, &wait); @@ -1994,7 +1997,6 @@ static ssize_t snd_timer_user_read(struct file *file, char __user *buffer, tu->qused--; spin_unlock_irq(&tu->qlock); - mutex_lock(&tu->ioctl_lock); if (tu->tread) { if (copy_to_user(buffer, &tu->tqueue[qhead], sizeof(struct snd_timer_tread))) @@ -2004,7 +2006,6 @@ static ssize_t snd_timer_user_read(struct file *file, char __user *buffer, sizeof(struct snd_timer_read))) err = -EFAULT; } - mutex_unlock(&tu->ioctl_lock); spin_lock_irq(&tu->qlock); if (err < 0) @@ -2014,6 +2015,7 @@ static ssize_t snd_timer_user_read(struct file *file, char __user *buffer, } _error: spin_unlock_irq(&tu->qlock); + mutex_unlock(&tu->ioctl_lock); return result > 0 ? result : err; }