From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id 9NVQELVYGVuTAwAAmS7hNA ; Thu, 07 Jun 2018 16:09:53 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id F1A2F6074D; Thu, 7 Jun 2018 16:09:52 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 351FA60590; Thu, 7 Jun 2018 16:09:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 351FA60590 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935508AbeFGQJK (ORCPT + 25 others); Thu, 7 Jun 2018 12:09:10 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:39204 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932872AbeFGOJC (ORCPT ); Thu, 7 Jun 2018 10:09:02 -0400 Received: from [148.252.241.226] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1fQvb1-0005Zr-RF; Thu, 07 Jun 2018 15:08:59 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1fQvax-0002i7-SG; Thu, 07 Jun 2018 15:08:55 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Nicolai Stange" , "Takashi Iwai" , "=?UTF-8?Q?=E8=8C=83=E9=BE=99=E9=A3=9E?=" Date: Thu, 07 Jun 2018 15:05:21 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 026/410] ALSA: seq: More protection for concurrent write and ioctl races In-Reply-To: X-SA-Exim-Connect-IP: 148.252.241.226 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.57-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit 7bd80091567789f1c0cb70eb4737aac8bcd2b6b9 upstream. This patch is an attempt for further hardening against races between the concurrent write and ioctls. The previous fix d15d662e89fc ("ALSA: seq: Fix racy pool initializations") covered the race of the pool initialization at writer and the pool resize ioctl by the client->ioctl_mutex (CVE-2018-1000004). However, basically this mutex should be applied more widely to the whole write operation for avoiding the unexpected pool operations by another thread. The only change outside snd_seq_write() is the additional mutex argument to helper functions, so that we can unlock / relock the given mutex temporarily during schedule() call for blocking write. Fixes: d15d662e89fc ("ALSA: seq: Fix racy pool initializations") Reported-by: 范龙飞 Reported-by: Nicolai Stange Reviewed-and-tested-by: Nicolai Stange Signed-off-by: Takashi Iwai Signed-off-by: Ben Hutchings --- sound/core/seq/seq_clientmgr.c | 18 +++++++++++------- sound/core/seq/seq_fifo.c | 2 +- sound/core/seq/seq_memory.c | 14 ++++++++++---- sound/core/seq/seq_memory.h | 3 ++- 4 files changed, 24 insertions(+), 13 deletions(-) --- a/sound/core/seq/seq_clientmgr.c +++ b/sound/core/seq/seq_clientmgr.c @@ -919,7 +919,8 @@ int snd_seq_dispatch_event(struct snd_se static int snd_seq_client_enqueue_event(struct snd_seq_client *client, struct snd_seq_event *event, struct file *file, int blocking, - int atomic, int hop) + int atomic, int hop, + struct mutex *mutexp) { struct snd_seq_event_cell *cell; int err; @@ -957,7 +958,8 @@ static int snd_seq_client_enqueue_event( return -ENXIO; /* queue is not allocated */ /* allocate an event cell */ - err = snd_seq_event_dup(client->pool, event, &cell, !blocking || atomic, file); + err = snd_seq_event_dup(client->pool, event, &cell, !blocking || atomic, + file, mutexp); if (err < 0) return err; @@ -1026,12 +1028,11 @@ static ssize_t snd_seq_write(struct file return -ENXIO; /* allocate the pool now if the pool is not allocated yet */ + mutex_lock(&client->ioctl_mutex); if (client->pool->size > 0 && !snd_seq_write_pool_allocated(client)) { - mutex_lock(&client->ioctl_mutex); err = snd_seq_pool_init(client->pool); - mutex_unlock(&client->ioctl_mutex); if (err < 0) - return -ENOMEM; + goto out; } /* only process whole events */ @@ -1082,7 +1083,7 @@ static ssize_t snd_seq_write(struct file /* ok, enqueue it */ err = snd_seq_client_enqueue_event(client, &event, file, !(file->f_flags & O_NONBLOCK), - 0, 0); + 0, 0, &client->ioctl_mutex); if (err < 0) break; @@ -1093,6 +1094,8 @@ static ssize_t snd_seq_write(struct file written += len; } + out: + mutex_unlock(&client->ioctl_mutex); return written ? written : err; } @@ -2355,7 +2358,8 @@ static int kernel_client_enqueue(int cli if (! cptr->accept_output) result = -EPERM; else /* send it */ - result = snd_seq_client_enqueue_event(cptr, ev, file, blocking, atomic, hop); + result = snd_seq_client_enqueue_event(cptr, ev, file, blocking, + atomic, hop, NULL); snd_seq_client_unlock(cptr); return result; --- a/sound/core/seq/seq_fifo.c +++ b/sound/core/seq/seq_fifo.c @@ -123,7 +123,7 @@ int snd_seq_fifo_event_in(struct snd_seq return -EINVAL; snd_use_lock_use(&f->use_lock); - err = snd_seq_event_dup(f->pool, event, &cell, 1, NULL); /* always non-blocking */ + err = snd_seq_event_dup(f->pool, event, &cell, 1, NULL, NULL); /* always non-blocking */ if (err < 0) { if ((err == -ENOMEM) || (err == -EAGAIN)) atomic_inc(&f->overflow); --- a/sound/core/seq/seq_memory.c +++ b/sound/core/seq/seq_memory.c @@ -221,7 +221,8 @@ void snd_seq_cell_free(struct snd_seq_ev */ static int snd_seq_cell_alloc(struct snd_seq_pool *pool, struct snd_seq_event_cell **cellp, - int nonblock, struct file *file) + int nonblock, struct file *file, + struct mutex *mutexp) { struct snd_seq_event_cell *cell; unsigned long flags; @@ -245,7 +246,11 @@ static int snd_seq_cell_alloc(struct snd set_current_state(TASK_INTERRUPTIBLE); add_wait_queue(&pool->output_sleep, &wait); spin_unlock_irq(&pool->lock); + if (mutexp) + mutex_unlock(mutexp); schedule(); + if (mutexp) + mutex_lock(mutexp); spin_lock_irq(&pool->lock); remove_wait_queue(&pool->output_sleep, &wait); /* interrupted? */ @@ -288,7 +293,7 @@ __error: */ int snd_seq_event_dup(struct snd_seq_pool *pool, struct snd_seq_event *event, struct snd_seq_event_cell **cellp, int nonblock, - struct file *file) + struct file *file, struct mutex *mutexp) { int ncells, err; unsigned int extlen; @@ -305,7 +310,7 @@ int snd_seq_event_dup(struct snd_seq_poo if (ncells >= pool->total_elements) return -ENOMEM; - err = snd_seq_cell_alloc(pool, &cell, nonblock, file); + err = snd_seq_cell_alloc(pool, &cell, nonblock, file, mutexp); if (err < 0) return err; @@ -331,7 +336,8 @@ int snd_seq_event_dup(struct snd_seq_poo int size = sizeof(struct snd_seq_event); if (len < size) size = len; - err = snd_seq_cell_alloc(pool, &tmp, nonblock, file); + err = snd_seq_cell_alloc(pool, &tmp, nonblock, file, + mutexp); if (err < 0) goto __error; if (cell->event.data.ext.ptr == NULL) --- a/sound/core/seq/seq_memory.h +++ b/sound/core/seq/seq_memory.h @@ -66,7 +66,8 @@ struct snd_seq_pool { void snd_seq_cell_free(struct snd_seq_event_cell *cell); int snd_seq_event_dup(struct snd_seq_pool *pool, struct snd_seq_event *event, - struct snd_seq_event_cell **cellp, int nonblock, struct file *file); + struct snd_seq_event_cell **cellp, int nonblock, + struct file *file, struct mutex *mutexp); /* return number of unused (free) cells */ static inline int snd_seq_unused_cells(struct snd_seq_pool *pool)