![Takashi Iwai](/assets/img/avatar_default.png)
The commit [7f0973e973
: ALSA: seq: Fix lockdep warnings due to double mutex locks] split the management of two linked lists (source and destination) into two individual calls for avoiding the AB/BA deadlock. However, this may leave the possible double deletion of one of two lists when the counterpart is being deleted concurrently. It ends up with a list corruption, as revealed by syzkaller fuzzer. This patch fixes it by checking the list emptiness and skipping the deletion and the following process. BugLink: http://lkml.kernel.org/r/CACT4Y+bay9qsrz6dQu31EcGaH9XwfW7o3oBzSQUG9fMszoh=Sg@mail.gmail.com Fixes:7f0973e973
('ALSA: seq: Fix lockdep warnings due to 'double mutex locks) Reported-by: Dmitry Vyukov <dvyukov@google.com> Tested-by: Dmitry Vyukov <dvyukov@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
711 lines
19 KiB
C
711 lines
19 KiB
C
/*
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* ALSA sequencer Ports
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* Copyright (c) 1998 by Frank van de Pol <fvdpol@coil.demon.nl>
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* Jaroslav Kysela <perex@perex.cz>
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*
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <sound/core.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include "seq_system.h"
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#include "seq_ports.h"
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#include "seq_clientmgr.h"
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/*
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registration of client ports
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*/
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/*
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NOTE: the current implementation of the port structure as a linked list is
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not optimal for clients that have many ports. For sending messages to all
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subscribers of a port we first need to find the address of the port
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structure, which means we have to traverse the list. A direct access table
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(array) would be better, but big preallocated arrays waste memory.
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Possible actions:
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1) leave it this way, a client does normaly does not have more than a few
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ports
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2) replace the linked list of ports by a array of pointers which is
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dynamicly kmalloced. When a port is added or deleted we can simply allocate
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a new array, copy the corresponding pointers, and delete the old one. We
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then only need a pointer to this array, and an integer that tells us how
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much elements are in array.
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*/
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/* return pointer to port structure - port is locked if found */
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struct snd_seq_client_port *snd_seq_port_use_ptr(struct snd_seq_client *client,
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int num)
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{
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struct snd_seq_client_port *port;
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if (client == NULL)
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return NULL;
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read_lock(&client->ports_lock);
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list_for_each_entry(port, &client->ports_list_head, list) {
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if (port->addr.port == num) {
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if (port->closing)
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break; /* deleting now */
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snd_use_lock_use(&port->use_lock);
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read_unlock(&client->ports_lock);
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return port;
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}
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}
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read_unlock(&client->ports_lock);
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return NULL; /* not found */
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}
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/* search for the next port - port is locked if found */
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struct snd_seq_client_port *snd_seq_port_query_nearest(struct snd_seq_client *client,
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struct snd_seq_port_info *pinfo)
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{
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int num;
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struct snd_seq_client_port *port, *found;
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num = pinfo->addr.port;
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found = NULL;
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read_lock(&client->ports_lock);
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list_for_each_entry(port, &client->ports_list_head, list) {
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if (port->addr.port < num)
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continue;
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if (port->addr.port == num) {
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found = port;
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break;
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}
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if (found == NULL || port->addr.port < found->addr.port)
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found = port;
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}
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if (found) {
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if (found->closing)
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found = NULL;
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else
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snd_use_lock_use(&found->use_lock);
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}
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read_unlock(&client->ports_lock);
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return found;
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}
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/* initialize snd_seq_port_subs_info */
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static void port_subs_info_init(struct snd_seq_port_subs_info *grp)
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{
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INIT_LIST_HEAD(&grp->list_head);
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grp->count = 0;
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grp->exclusive = 0;
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rwlock_init(&grp->list_lock);
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init_rwsem(&grp->list_mutex);
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grp->open = NULL;
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grp->close = NULL;
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}
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/* create a port, port number is returned (-1 on failure) */
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struct snd_seq_client_port *snd_seq_create_port(struct snd_seq_client *client,
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int port)
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{
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unsigned long flags;
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struct snd_seq_client_port *new_port, *p;
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int num = -1;
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/* sanity check */
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if (snd_BUG_ON(!client))
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return NULL;
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if (client->num_ports >= SNDRV_SEQ_MAX_PORTS) {
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pr_warn("ALSA: seq: too many ports for client %d\n", client->number);
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return NULL;
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}
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/* create a new port */
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new_port = kzalloc(sizeof(*new_port), GFP_KERNEL);
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if (!new_port)
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return NULL; /* failure, out of memory */
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/* init port data */
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new_port->addr.client = client->number;
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new_port->addr.port = -1;
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new_port->owner = THIS_MODULE;
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sprintf(new_port->name, "port-%d", num);
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snd_use_lock_init(&new_port->use_lock);
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port_subs_info_init(&new_port->c_src);
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port_subs_info_init(&new_port->c_dest);
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num = port >= 0 ? port : 0;
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mutex_lock(&client->ports_mutex);
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write_lock_irqsave(&client->ports_lock, flags);
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list_for_each_entry(p, &client->ports_list_head, list) {
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if (p->addr.port > num)
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break;
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if (port < 0) /* auto-probe mode */
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num = p->addr.port + 1;
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}
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/* insert the new port */
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list_add_tail(&new_port->list, &p->list);
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client->num_ports++;
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new_port->addr.port = num; /* store the port number in the port */
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write_unlock_irqrestore(&client->ports_lock, flags);
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mutex_unlock(&client->ports_mutex);
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sprintf(new_port->name, "port-%d", num);
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return new_port;
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}
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/* */
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static int subscribe_port(struct snd_seq_client *client,
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struct snd_seq_client_port *port,
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struct snd_seq_port_subs_info *grp,
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struct snd_seq_port_subscribe *info, int send_ack);
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static int unsubscribe_port(struct snd_seq_client *client,
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struct snd_seq_client_port *port,
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struct snd_seq_port_subs_info *grp,
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struct snd_seq_port_subscribe *info, int send_ack);
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static struct snd_seq_client_port *get_client_port(struct snd_seq_addr *addr,
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struct snd_seq_client **cp)
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{
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struct snd_seq_client_port *p;
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*cp = snd_seq_client_use_ptr(addr->client);
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if (*cp) {
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p = snd_seq_port_use_ptr(*cp, addr->port);
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if (! p) {
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snd_seq_client_unlock(*cp);
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*cp = NULL;
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}
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return p;
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}
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return NULL;
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}
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static void delete_and_unsubscribe_port(struct snd_seq_client *client,
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struct snd_seq_client_port *port,
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struct snd_seq_subscribers *subs,
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bool is_src, bool ack);
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static inline struct snd_seq_subscribers *
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get_subscriber(struct list_head *p, bool is_src)
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{
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if (is_src)
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return list_entry(p, struct snd_seq_subscribers, src_list);
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else
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return list_entry(p, struct snd_seq_subscribers, dest_list);
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}
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/*
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* remove all subscribers on the list
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* this is called from port_delete, for each src and dest list.
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*/
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static void clear_subscriber_list(struct snd_seq_client *client,
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struct snd_seq_client_port *port,
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struct snd_seq_port_subs_info *grp,
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int is_src)
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{
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struct list_head *p, *n;
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list_for_each_safe(p, n, &grp->list_head) {
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struct snd_seq_subscribers *subs;
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struct snd_seq_client *c;
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struct snd_seq_client_port *aport;
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subs = get_subscriber(p, is_src);
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if (is_src)
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aport = get_client_port(&subs->info.dest, &c);
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else
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aport = get_client_port(&subs->info.sender, &c);
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delete_and_unsubscribe_port(client, port, subs, is_src, false);
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if (!aport) {
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/* looks like the connected port is being deleted.
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* we decrease the counter, and when both ports are deleted
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* remove the subscriber info
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*/
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if (atomic_dec_and_test(&subs->ref_count))
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kfree(subs);
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continue;
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}
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/* ok we got the connected port */
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delete_and_unsubscribe_port(c, aport, subs, !is_src, true);
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kfree(subs);
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snd_seq_port_unlock(aport);
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snd_seq_client_unlock(c);
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}
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}
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/* delete port data */
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static int port_delete(struct snd_seq_client *client,
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struct snd_seq_client_port *port)
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{
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/* set closing flag and wait for all port access are gone */
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port->closing = 1;
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snd_use_lock_sync(&port->use_lock);
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/* clear subscribers info */
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clear_subscriber_list(client, port, &port->c_src, true);
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clear_subscriber_list(client, port, &port->c_dest, false);
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if (port->private_free)
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port->private_free(port->private_data);
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snd_BUG_ON(port->c_src.count != 0);
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snd_BUG_ON(port->c_dest.count != 0);
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kfree(port);
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return 0;
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}
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/* delete a port with the given port id */
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int snd_seq_delete_port(struct snd_seq_client *client, int port)
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{
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unsigned long flags;
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struct snd_seq_client_port *found = NULL, *p;
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mutex_lock(&client->ports_mutex);
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write_lock_irqsave(&client->ports_lock, flags);
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list_for_each_entry(p, &client->ports_list_head, list) {
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if (p->addr.port == port) {
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/* ok found. delete from the list at first */
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list_del(&p->list);
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client->num_ports--;
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found = p;
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break;
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}
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}
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write_unlock_irqrestore(&client->ports_lock, flags);
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mutex_unlock(&client->ports_mutex);
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if (found)
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return port_delete(client, found);
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else
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return -ENOENT;
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}
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/* delete the all ports belonging to the given client */
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int snd_seq_delete_all_ports(struct snd_seq_client *client)
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{
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unsigned long flags;
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struct list_head deleted_list;
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struct snd_seq_client_port *port, *tmp;
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/* move the port list to deleted_list, and
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* clear the port list in the client data.
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*/
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mutex_lock(&client->ports_mutex);
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write_lock_irqsave(&client->ports_lock, flags);
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if (! list_empty(&client->ports_list_head)) {
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list_add(&deleted_list, &client->ports_list_head);
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list_del_init(&client->ports_list_head);
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} else {
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INIT_LIST_HEAD(&deleted_list);
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}
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client->num_ports = 0;
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write_unlock_irqrestore(&client->ports_lock, flags);
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/* remove each port in deleted_list */
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list_for_each_entry_safe(port, tmp, &deleted_list, list) {
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list_del(&port->list);
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snd_seq_system_client_ev_port_exit(port->addr.client, port->addr.port);
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port_delete(client, port);
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}
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mutex_unlock(&client->ports_mutex);
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return 0;
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}
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/* set port info fields */
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int snd_seq_set_port_info(struct snd_seq_client_port * port,
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struct snd_seq_port_info * info)
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{
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if (snd_BUG_ON(!port || !info))
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return -EINVAL;
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/* set port name */
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if (info->name[0])
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strlcpy(port->name, info->name, sizeof(port->name));
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/* set capabilities */
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port->capability = info->capability;
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/* get port type */
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port->type = info->type;
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/* information about supported channels/voices */
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port->midi_channels = info->midi_channels;
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port->midi_voices = info->midi_voices;
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port->synth_voices = info->synth_voices;
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/* timestamping */
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port->timestamping = (info->flags & SNDRV_SEQ_PORT_FLG_TIMESTAMP) ? 1 : 0;
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port->time_real = (info->flags & SNDRV_SEQ_PORT_FLG_TIME_REAL) ? 1 : 0;
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port->time_queue = info->time_queue;
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return 0;
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}
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/* get port info fields */
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int snd_seq_get_port_info(struct snd_seq_client_port * port,
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struct snd_seq_port_info * info)
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{
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if (snd_BUG_ON(!port || !info))
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return -EINVAL;
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/* get port name */
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strlcpy(info->name, port->name, sizeof(info->name));
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/* get capabilities */
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info->capability = port->capability;
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/* get port type */
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info->type = port->type;
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/* information about supported channels/voices */
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info->midi_channels = port->midi_channels;
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info->midi_voices = port->midi_voices;
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info->synth_voices = port->synth_voices;
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/* get subscriber counts */
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info->read_use = port->c_src.count;
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info->write_use = port->c_dest.count;
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/* timestamping */
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info->flags = 0;
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if (port->timestamping) {
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info->flags |= SNDRV_SEQ_PORT_FLG_TIMESTAMP;
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if (port->time_real)
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info->flags |= SNDRV_SEQ_PORT_FLG_TIME_REAL;
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info->time_queue = port->time_queue;
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}
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return 0;
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}
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/*
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* call callback functions (if any):
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* the callbacks are invoked only when the first (for connection) or
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* the last subscription (for disconnection) is done. Second or later
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* subscription results in increment of counter, but no callback is
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* invoked.
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* This feature is useful if these callbacks are associated with
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* initialization or termination of devices (see seq_midi.c).
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*/
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static int subscribe_port(struct snd_seq_client *client,
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struct snd_seq_client_port *port,
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struct snd_seq_port_subs_info *grp,
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struct snd_seq_port_subscribe *info,
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int send_ack)
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{
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int err = 0;
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if (!try_module_get(port->owner))
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return -EFAULT;
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grp->count++;
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if (grp->open && grp->count == 1) {
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err = grp->open(port->private_data, info);
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if (err < 0) {
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module_put(port->owner);
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grp->count--;
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}
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}
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if (err >= 0 && send_ack && client->type == USER_CLIENT)
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snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
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info, SNDRV_SEQ_EVENT_PORT_SUBSCRIBED);
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return err;
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}
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static int unsubscribe_port(struct snd_seq_client *client,
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struct snd_seq_client_port *port,
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struct snd_seq_port_subs_info *grp,
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struct snd_seq_port_subscribe *info,
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int send_ack)
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{
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int err = 0;
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if (! grp->count)
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return -EINVAL;
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grp->count--;
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if (grp->close && grp->count == 0)
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err = grp->close(port->private_data, info);
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if (send_ack && client->type == USER_CLIENT)
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snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
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info, SNDRV_SEQ_EVENT_PORT_UNSUBSCRIBED);
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module_put(port->owner);
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return err;
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}
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/* check if both addresses are identical */
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static inline int addr_match(struct snd_seq_addr *r, struct snd_seq_addr *s)
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{
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return (r->client == s->client) && (r->port == s->port);
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}
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/* check the two subscribe info match */
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/* if flags is zero, checks only sender and destination addresses */
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static int match_subs_info(struct snd_seq_port_subscribe *r,
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struct snd_seq_port_subscribe *s)
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{
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if (addr_match(&r->sender, &s->sender) &&
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addr_match(&r->dest, &s->dest)) {
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if (r->flags && r->flags == s->flags)
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return r->queue == s->queue;
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else if (! r->flags)
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return 1;
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}
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return 0;
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}
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static int check_and_subscribe_port(struct snd_seq_client *client,
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struct snd_seq_client_port *port,
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struct snd_seq_subscribers *subs,
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bool is_src, bool exclusive, bool ack)
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{
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struct snd_seq_port_subs_info *grp;
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struct list_head *p;
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struct snd_seq_subscribers *s;
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int err;
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grp = is_src ? &port->c_src : &port->c_dest;
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err = -EBUSY;
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down_write(&grp->list_mutex);
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if (exclusive) {
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if (!list_empty(&grp->list_head))
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goto __error;
|
|
} else {
|
|
if (grp->exclusive)
|
|
goto __error;
|
|
/* check whether already exists */
|
|
list_for_each(p, &grp->list_head) {
|
|
s = get_subscriber(p, is_src);
|
|
if (match_subs_info(&subs->info, &s->info))
|
|
goto __error;
|
|
}
|
|
}
|
|
|
|
err = subscribe_port(client, port, grp, &subs->info, ack);
|
|
if (err < 0) {
|
|
grp->exclusive = 0;
|
|
goto __error;
|
|
}
|
|
|
|
/* add to list */
|
|
write_lock_irq(&grp->list_lock);
|
|
if (is_src)
|
|
list_add_tail(&subs->src_list, &grp->list_head);
|
|
else
|
|
list_add_tail(&subs->dest_list, &grp->list_head);
|
|
grp->exclusive = exclusive;
|
|
atomic_inc(&subs->ref_count);
|
|
write_unlock_irq(&grp->list_lock);
|
|
err = 0;
|
|
|
|
__error:
|
|
up_write(&grp->list_mutex);
|
|
return err;
|
|
}
|
|
|
|
static void delete_and_unsubscribe_port(struct snd_seq_client *client,
|
|
struct snd_seq_client_port *port,
|
|
struct snd_seq_subscribers *subs,
|
|
bool is_src, bool ack)
|
|
{
|
|
struct snd_seq_port_subs_info *grp;
|
|
struct list_head *list;
|
|
bool empty;
|
|
|
|
grp = is_src ? &port->c_src : &port->c_dest;
|
|
list = is_src ? &subs->src_list : &subs->dest_list;
|
|
down_write(&grp->list_mutex);
|
|
write_lock_irq(&grp->list_lock);
|
|
empty = list_empty(list);
|
|
if (!empty)
|
|
list_del_init(list);
|
|
grp->exclusive = 0;
|
|
write_unlock_irq(&grp->list_lock);
|
|
up_write(&grp->list_mutex);
|
|
|
|
if (!empty)
|
|
unsubscribe_port(client, port, grp, &subs->info, ack);
|
|
}
|
|
|
|
/* connect two ports */
|
|
int snd_seq_port_connect(struct snd_seq_client *connector,
|
|
struct snd_seq_client *src_client,
|
|
struct snd_seq_client_port *src_port,
|
|
struct snd_seq_client *dest_client,
|
|
struct snd_seq_client_port *dest_port,
|
|
struct snd_seq_port_subscribe *info)
|
|
{
|
|
struct snd_seq_subscribers *subs;
|
|
bool exclusive;
|
|
int err;
|
|
|
|
subs = kzalloc(sizeof(*subs), GFP_KERNEL);
|
|
if (!subs)
|
|
return -ENOMEM;
|
|
|
|
subs->info = *info;
|
|
atomic_set(&subs->ref_count, 0);
|
|
INIT_LIST_HEAD(&subs->src_list);
|
|
INIT_LIST_HEAD(&subs->dest_list);
|
|
|
|
exclusive = !!(info->flags & SNDRV_SEQ_PORT_SUBS_EXCLUSIVE);
|
|
|
|
err = check_and_subscribe_port(src_client, src_port, subs, true,
|
|
exclusive,
|
|
connector->number != src_client->number);
|
|
if (err < 0)
|
|
goto error;
|
|
err = check_and_subscribe_port(dest_client, dest_port, subs, false,
|
|
exclusive,
|
|
connector->number != dest_client->number);
|
|
if (err < 0)
|
|
goto error_dest;
|
|
|
|
return 0;
|
|
|
|
error_dest:
|
|
delete_and_unsubscribe_port(src_client, src_port, subs, true,
|
|
connector->number != src_client->number);
|
|
error:
|
|
kfree(subs);
|
|
return err;
|
|
}
|
|
|
|
/* remove the connection */
|
|
int snd_seq_port_disconnect(struct snd_seq_client *connector,
|
|
struct snd_seq_client *src_client,
|
|
struct snd_seq_client_port *src_port,
|
|
struct snd_seq_client *dest_client,
|
|
struct snd_seq_client_port *dest_port,
|
|
struct snd_seq_port_subscribe *info)
|
|
{
|
|
struct snd_seq_port_subs_info *src = &src_port->c_src;
|
|
struct snd_seq_subscribers *subs;
|
|
int err = -ENOENT;
|
|
|
|
down_write(&src->list_mutex);
|
|
/* look for the connection */
|
|
list_for_each_entry(subs, &src->list_head, src_list) {
|
|
if (match_subs_info(info, &subs->info)) {
|
|
atomic_dec(&subs->ref_count); /* mark as not ready */
|
|
err = 0;
|
|
break;
|
|
}
|
|
}
|
|
up_write(&src->list_mutex);
|
|
if (err < 0)
|
|
return err;
|
|
|
|
delete_and_unsubscribe_port(src_client, src_port, subs, true,
|
|
connector->number != src_client->number);
|
|
delete_and_unsubscribe_port(dest_client, dest_port, subs, false,
|
|
connector->number != dest_client->number);
|
|
kfree(subs);
|
|
return 0;
|
|
}
|
|
|
|
|
|
/* get matched subscriber */
|
|
struct snd_seq_subscribers *snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp,
|
|
struct snd_seq_addr *dest_addr)
|
|
{
|
|
struct snd_seq_subscribers *s, *found = NULL;
|
|
|
|
down_read(&src_grp->list_mutex);
|
|
list_for_each_entry(s, &src_grp->list_head, src_list) {
|
|
if (addr_match(dest_addr, &s->info.dest)) {
|
|
found = s;
|
|
break;
|
|
}
|
|
}
|
|
up_read(&src_grp->list_mutex);
|
|
return found;
|
|
}
|
|
|
|
/*
|
|
* Attach a device driver that wants to receive events from the
|
|
* sequencer. Returns the new port number on success.
|
|
* A driver that wants to receive the events converted to midi, will
|
|
* use snd_seq_midisynth_register_port().
|
|
*/
|
|
/* exported */
|
|
int snd_seq_event_port_attach(int client,
|
|
struct snd_seq_port_callback *pcbp,
|
|
int cap, int type, int midi_channels,
|
|
int midi_voices, char *portname)
|
|
{
|
|
struct snd_seq_port_info portinfo;
|
|
int ret;
|
|
|
|
/* Set up the port */
|
|
memset(&portinfo, 0, sizeof(portinfo));
|
|
portinfo.addr.client = client;
|
|
strlcpy(portinfo.name, portname ? portname : "Unamed port",
|
|
sizeof(portinfo.name));
|
|
|
|
portinfo.capability = cap;
|
|
portinfo.type = type;
|
|
portinfo.kernel = pcbp;
|
|
portinfo.midi_channels = midi_channels;
|
|
portinfo.midi_voices = midi_voices;
|
|
|
|
/* Create it */
|
|
ret = snd_seq_kernel_client_ctl(client,
|
|
SNDRV_SEQ_IOCTL_CREATE_PORT,
|
|
&portinfo);
|
|
|
|
if (ret >= 0)
|
|
ret = portinfo.addr.port;
|
|
|
|
return ret;
|
|
}
|
|
|
|
EXPORT_SYMBOL(snd_seq_event_port_attach);
|
|
|
|
/*
|
|
* Detach the driver from a port.
|
|
*/
|
|
/* exported */
|
|
int snd_seq_event_port_detach(int client, int port)
|
|
{
|
|
struct snd_seq_port_info portinfo;
|
|
int err;
|
|
|
|
memset(&portinfo, 0, sizeof(portinfo));
|
|
portinfo.addr.client = client;
|
|
portinfo.addr.port = port;
|
|
err = snd_seq_kernel_client_ctl(client,
|
|
SNDRV_SEQ_IOCTL_DELETE_PORT,
|
|
&portinfo);
|
|
|
|
return err;
|
|
}
|
|
|
|
EXPORT_SYMBOL(snd_seq_event_port_detach);
|