From eccc92a34d4809cd5926fa054ff7d231ae890c5e Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Mon, 30 Jan 2006 14:41:51 +0000
Subject: [PATCH] Fix infinite parse of recursive definitions

Fixed the infinite parse (and eventually segfault) of recursive definitions.
Also fixed the parse of a string slave PCM of direct plugins.
---
 include/local.h            |  5 +++++
 src/conf.c                 | 19 +++++++++++++++++++
 src/pcm/pcm.c              | 17 ++++++++++++-----
 src/pcm/pcm_adpcm.c        |  2 +-
 src/pcm/pcm_alaw.c         |  2 +-
 src/pcm/pcm_asym.c         |  2 +-
 src/pcm/pcm_copy.c         |  2 +-
 src/pcm/pcm_direct.c       | 31 ++++++++++++++++++++++++++++++-
 src/pcm/pcm_direct.h       |  2 +-
 src/pcm/pcm_dmix.c         |  7 +++++--
 src/pcm/pcm_dshare.c       |  7 +++++--
 src/pcm/pcm_dsnoop.c       |  7 +++++--
 src/pcm/pcm_extplug.c      |  2 +-
 src/pcm/pcm_file.c         |  2 +-
 src/pcm/pcm_hooks.c        |  2 +-
 src/pcm/pcm_iec958.c       |  2 +-
 src/pcm/pcm_ladspa.c       |  2 +-
 src/pcm/pcm_lfloat.c       |  2 +-
 src/pcm/pcm_linear.c       |  2 +-
 src/pcm/pcm_local.h        |  2 +-
 src/pcm/pcm_meter.c        |  2 +-
 src/pcm/pcm_mulaw.c        |  2 +-
 src/pcm/pcm_multi.c        |  4 +++-
 src/pcm/pcm_plug.c         |  2 +-
 src/pcm/pcm_rate.c         |  2 +-
 src/pcm/pcm_route.c        |  2 +-
 src/pcm/pcm_softvol.c      |  2 +-
 src/rawmidi/rawmidi_virt.c |  7 ++++++-
 src/seq/seq.c              | 21 ++++++++++++++++++---
 29 files changed, 127 insertions(+), 36 deletions(-)

diff --git a/include/local.h b/include/local.h
index bf53d512..b18d77a9 100644
--- a/include/local.h
+++ b/include/local.h
@@ -249,4 +249,9 @@ void *snd_dlobj_cache_lookup(const char *name);
 int snd_dlobj_cache_add(const char *name, void *dlobj, void *open_func);
 void snd_dlobj_cache_cleanup(void);
 
+/* for recursive checks */
+void snd_config_set_hop(snd_config_t *conf, int hop);
+int snd_config_check_hop(snd_config_t *conf);
+#define SND_CONF_MAX_HOPS	64
+
 #endif
diff --git a/src/conf.c b/src/conf.c
index 78cc4cb3..3667ac06 100644
--- a/src/conf.c
+++ b/src/conf.c
@@ -440,6 +440,7 @@ struct _snd_config {
 	} u;
 	struct list_head list;
 	snd_config_t *father;
+	int hop;
 };
 
 struct filedesc {
@@ -4011,6 +4012,24 @@ int snd_config_search_definition(snd_config_t *config,
 	return snd_config_expand(conf, config, args, NULL, result);
 }
 
+#ifndef DOC_HIDDEN
+void snd_config_set_hop(snd_config_t *conf, int hop)
+{
+	conf->hop = hop;
+}
+
+int snd_config_check_hop(snd_config_t *conf)
+{
+	if (conf) {
+		if (conf->hop >= SND_CONF_MAX_HOPS) {
+			SYSERR("Too many definition levels (looped?)\n");
+			return -EINVAL;
+		}
+		return conf->hop;
+	}
+	return 0;
+}
+#endif
 
 #if 0
 /* Not strictly needed, but useful to check for memory leaks */
diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
index b3f3e6bd..6974aa0b 100644
--- a/src/pcm/pcm.c
+++ b/src/pcm/pcm.c
@@ -2098,7 +2098,8 @@ static int snd_pcm_open_conf(snd_pcm_t **pcmp, const char *name,
 }
 
 static int snd_pcm_open_noupdate(snd_pcm_t **pcmp, snd_config_t *root,
-				 const char *name, snd_pcm_stream_t stream, int mode)
+				 const char *name, snd_pcm_stream_t stream,
+				 int mode, int hop)
 {
 	int err;
 	snd_config_t *pcm_conf;
@@ -2107,6 +2108,7 @@ static int snd_pcm_open_noupdate(snd_pcm_t **pcmp, snd_config_t *root,
 		SNDERR("Unknown PCM %s", name);
 		return err;
 	}
+	snd_config_set_hop(pcm_conf, hop);
 	err = snd_pcm_open_conf(pcmp, name, root, pcm_conf, stream, mode);
 	snd_config_delete(pcm_conf);
 	return err;
@@ -2128,7 +2130,7 @@ int snd_pcm_open(snd_pcm_t **pcmp, const char *name,
 	err = snd_config_update();
 	if (err < 0)
 		return err;
-	return snd_pcm_open_noupdate(pcmp, snd_config, name, stream, mode);
+	return snd_pcm_open_noupdate(pcmp, snd_config, name, stream, mode, 0);
 }
 
 /**
@@ -2145,7 +2147,7 @@ int snd_pcm_open_lconf(snd_pcm_t **pcmp, const char *name,
 		       snd_config_t *lconf)
 {
 	assert(pcmp && name && lconf);
-	return snd_pcm_open_noupdate(pcmp, lconf, name, stream, mode);
+	return snd_pcm_open_noupdate(pcmp, lconf, name, stream, mode, 0);
 }
 
 #ifndef DOC_HIDDEN
@@ -2187,11 +2189,16 @@ int snd_pcm_free(snd_pcm_t *pcm)
 
 int snd_pcm_open_slave(snd_pcm_t **pcmp, snd_config_t *root,
 		       snd_config_t *conf, snd_pcm_stream_t stream,
-		       int mode)
+		       int mode, snd_config_t *parent_conf)
 {
 	const char *str;
+	int hop;
+
+	if ((hop = snd_config_check_hop(parent_conf)) < 0)
+		return hop;
 	if (snd_config_get_string(conf, &str) >= 0)
-		return snd_pcm_open_noupdate(pcmp, root, str, stream, mode);
+		return snd_pcm_open_noupdate(pcmp, root, str, stream, mode,
+					     hop + 1);
 	return snd_pcm_open_conf(pcmp, NULL, root, conf, stream, mode);
 }
 #endif
diff --git a/src/pcm/pcm_adpcm.c b/src/pcm/pcm_adpcm.c
index e5cb4506..8350dbec 100644
--- a/src/pcm/pcm_adpcm.c
+++ b/src/pcm/pcm_adpcm.c
@@ -666,7 +666,7 @@ int _snd_pcm_adpcm_open(snd_pcm_t **pcmp, const char *name,
 		SNDERR("invalid slave format");
 		return -EINVAL;
 	}
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	if (err < 0)
 		return err;
diff --git a/src/pcm/pcm_alaw.c b/src/pcm/pcm_alaw.c
index 19045ec8..767e69fd 100644
--- a/src/pcm/pcm_alaw.c
+++ b/src/pcm/pcm_alaw.c
@@ -538,7 +538,7 @@ int _snd_pcm_alaw_open(snd_pcm_t **pcmp, const char *name,
 		SNDERR("invalid slave format");
 		return -EINVAL;
 	}
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	if (err < 0)
 		return err;
diff --git a/src/pcm/pcm_asym.c b/src/pcm/pcm_asym.c
index 5a2a4d64..660f3107 100644
--- a/src/pcm/pcm_asym.c
+++ b/src/pcm/pcm_asym.c
@@ -109,7 +109,7 @@ int _snd_pcm_asym_open(snd_pcm_t **pcmp, const char *name ATTRIBUTE_UNUSED,
 	err = snd_pcm_slave_conf(root, slave, &sconf, 0);
 	if (err < 0)
 		return err;
-	err = snd_pcm_open_slave(pcmp, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(pcmp, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	return err;
 }
diff --git a/src/pcm/pcm_copy.c b/src/pcm/pcm_copy.c
index 1e8510f4..b1525bfa 100644
--- a/src/pcm/pcm_copy.c
+++ b/src/pcm/pcm_copy.c
@@ -284,7 +284,7 @@ int _snd_pcm_copy_open(snd_pcm_t **pcmp, const char *name,
 	err = snd_pcm_slave_conf(root, slave, &sconf, 0);
 	if (err < 0)
 		return err;
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	if (err < 0)
 		return err;
diff --git a/src/pcm/pcm_direct.c b/src/pcm/pcm_direct.c
index 113930e1..ff4bddbf 100644
--- a/src/pcm/pcm_direct.c
+++ b/src/pcm/pcm_direct.c
@@ -1260,11 +1260,34 @@ int snd_pcm_direct_parse_bindings(snd_pcm_direct_t *dmix, snd_config_t *cfg)
 /*
  * parse slave config and calculate the ipc_key offset
  */
-int snd_pcm_direct_get_slave_ipc_offset(snd_config_t *sconf, int direction)
+
+static int _snd_pcm_direct_get_slave_ipc_offset(snd_config_t *root,
+						snd_config_t *sconf,
+						int direction,
+						int hop)
 {
 	snd_config_iterator_t i, next;
 	int err;
 	long card = 0, device = 0, subdevice = 0;
+	const char *str;
+
+	if (snd_config_get_string(sconf, &str) >= 0) {
+		snd_config_t *pcm_conf;
+		if (hop > SND_CONF_MAX_HOPS) {
+			SNDERR("Too many definition levels (looped?)");
+			return -EINVAL;
+		}
+		err = snd_config_search_definition(root, "pcm", str, &pcm_conf);
+		if (err < 0) {
+			SNDERR("Unknown slave PCM %s", str);
+			return err;
+		}
+		err = _snd_pcm_direct_get_slave_ipc_offset(root, pcm_conf,
+							   direction,
+							   hop + 1);
+		snd_config_delete(pcm_conf);
+		return err;
+	}
 
 	snd_config_for_each(i, next, sconf) {
 		snd_config_t *n = snd_config_iterator_entry(i);
@@ -1325,6 +1348,12 @@ int snd_pcm_direct_get_slave_ipc_offset(snd_config_t *sconf, int direction)
 	return direction + (card << 1) + (device << 4) + (subdevice << 8);
 }
 
+int snd_pcm_direct_get_slave_ipc_offset(snd_config_t *root,
+					snd_config_t *sconf,
+					int direction)
+{
+	return _snd_pcm_direct_get_slave_ipc_offset(root, sconf, direction, 0);
+}
 
 int snd_pcm_direct_parse_open_conf(snd_config_t *conf, struct snd_pcm_direct_open_conf *rec)
 {
diff --git a/src/pcm/pcm_direct.h b/src/pcm/pcm_direct.h
index 6a8bf791..31d3c4a9 100644
--- a/src/pcm/pcm_direct.h
+++ b/src/pcm/pcm_direct.h
@@ -186,7 +186,7 @@ int snd_pcm_direct_timer_stop(snd_pcm_direct_t *dmix);
 void snd_pcm_direct_clear_timer_queue(snd_pcm_direct_t *dmix);
 int snd_pcm_direct_set_timer_params(snd_pcm_direct_t *dmix);
 int snd_pcm_direct_open_secondary_client(snd_pcm_t **spcmp, snd_pcm_direct_t *dmix, const char *client_name);
-int snd_pcm_direct_get_slave_ipc_offset(snd_config_t *sconf, int direction);
+int snd_pcm_direct_get_slave_ipc_offset(snd_config_t *root, snd_config_t *sconf, int direction);
 
 int snd_timer_async(snd_timer_t *timer, int sig, pid_t pid);
 struct timespec snd_pcm_hw_fast_tstamp(snd_pcm_t *pcm);
diff --git a/src/pcm/pcm_dmix.c b/src/pcm/pcm_dmix.c
index 4f61a368..41a6bd8f 100644
--- a/src/pcm/pcm_dmix.c
+++ b/src/pcm/pcm_dmix.c
@@ -847,7 +847,10 @@ int snd_pcm_dmix_open(snd_pcm_t **pcmp, const char *name,
 	dmix->sync_ptr = snd_pcm_dmix_sync_ptr;
 
 	if (first_instance) {
-		ret = snd_pcm_open_slave(&spcm, root, sconf, stream, mode | SND_PCM_NONBLOCK);
+		/* recursion is already checked in
+		   snd_pcm_direct_get_slave_ipc_offset() */
+		ret = snd_pcm_open_slave(&spcm, root, sconf, stream,
+					 mode | SND_PCM_NONBLOCK, NULL);
 		if (ret < 0) {
 			SNDERR("unable to open slave");
 			goto _err;
@@ -1124,7 +1127,7 @@ int _snd_pcm_dmix_open(snd_pcm_t **pcmp, const char *name,
 	params.period_size = psize;
 	params.buffer_size = bsize;
 
-	ipc_offset = snd_pcm_direct_get_slave_ipc_offset(sconf, stream);
+	ipc_offset = snd_pcm_direct_get_slave_ipc_offset(root, sconf, stream);
 	if (ipc_offset < 0) {
 		snd_config_delete(sconf);
 		return ipc_offset;
diff --git a/src/pcm/pcm_dshare.c b/src/pcm/pcm_dshare.c
index c7cd9922..2d719dc9 100644
--- a/src/pcm/pcm_dshare.c
+++ b/src/pcm/pcm_dshare.c
@@ -672,7 +672,10 @@ int snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
 	dshare->sync_ptr = snd_pcm_dshare_sync_ptr;
 
 	if (first_instance) {
-		ret = snd_pcm_open_slave(&spcm, root, sconf, stream, mode | SND_PCM_NONBLOCK);
+		/* recursion is already checked in
+		   snd_pcm_direct_get_slave_ipc_offset() */
+		ret = snd_pcm_open_slave(&spcm, root, sconf, stream,
+					 mode | SND_PCM_NONBLOCK, NULL);
 		if (ret < 0) {
 			SNDERR("unable to open slave");
 			goto _err;
@@ -873,7 +876,7 @@ int _snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
 	params.period_size = psize;
 	params.buffer_size = bsize;
 
-	ipc_offset = snd_pcm_direct_get_slave_ipc_offset(sconf, stream);
+	ipc_offset = snd_pcm_direct_get_slave_ipc_offset(root, sconf, stream);
 	if (ipc_offset < 0) {
 		snd_config_delete(sconf);
 		return ipc_offset;
diff --git a/src/pcm/pcm_dsnoop.c b/src/pcm/pcm_dsnoop.c
index 6fe1bd52..e2b91bbe 100644
--- a/src/pcm/pcm_dsnoop.c
+++ b/src/pcm/pcm_dsnoop.c
@@ -554,7 +554,10 @@ int snd_pcm_dsnoop_open(snd_pcm_t **pcmp, const char *name,
 	dsnoop->sync_ptr = snd_pcm_dsnoop_sync_ptr;
 
 	if (first_instance) {
-		ret = snd_pcm_open_slave(&spcm, root, sconf, stream, mode | SND_PCM_NONBLOCK);
+		/* recursion is already checked in
+		   snd_pcm_direct_get_slave_ipc_offset() */
+		ret = snd_pcm_open_slave(&spcm, root, sconf, stream,
+					 mode | SND_PCM_NONBLOCK, NULL);
 		if (ret < 0) {
 			SNDERR("unable to open slave");
 			goto _err;
@@ -745,7 +748,7 @@ int _snd_pcm_dsnoop_open(snd_pcm_t **pcmp, const char *name,
 	params.period_size = psize;
 	params.buffer_size = bsize;
 
-	ipc_offset = snd_pcm_direct_get_slave_ipc_offset(sconf, stream);
+	ipc_offset = snd_pcm_direct_get_slave_ipc_offset(root, sconf, stream);
 	if (ipc_offset < 0) {
 		snd_config_delete(sconf);
 		return ipc_offset;
diff --git a/src/pcm/pcm_extplug.c b/src/pcm/pcm_extplug.c
index 36d4d248..2bde9e5b 100644
--- a/src/pcm/pcm_extplug.c
+++ b/src/pcm/pcm_extplug.c
@@ -622,7 +622,7 @@ int snd_pcm_extplug_create(snd_pcm_extplug_t *extplug, const char *name,
 	err = snd_pcm_slave_conf(root, slave_conf, &sconf, 0);
 	if (err < 0)
 		return err;
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, NULL);
 	snd_config_delete(sconf);
 	if (err < 0)
 		return err;
diff --git a/src/pcm/pcm_file.c b/src/pcm/pcm_file.c
index 4560bf4a..18951cc2 100644
--- a/src/pcm/pcm_file.c
+++ b/src/pcm/pcm_file.c
@@ -556,7 +556,7 @@ int _snd_pcm_file_open(snd_pcm_t **pcmp, const char *name,
 		SNDERR("file is not defined");
 		return -EINVAL;
 	}
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	if (err < 0)
 		return err;
diff --git a/src/pcm/pcm_hooks.c b/src/pcm/pcm_hooks.c
index ce5f221c..f5136862 100644
--- a/src/pcm/pcm_hooks.c
+++ b/src/pcm/pcm_hooks.c
@@ -460,7 +460,7 @@ int _snd_pcm_hooks_open(snd_pcm_t **pcmp, const char *name,
 	err = snd_pcm_slave_conf(root, slave, &sconf, 0);
 	if (err < 0)
 		return err;
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	if (err < 0)
 		return err;
diff --git a/src/pcm/pcm_iec958.c b/src/pcm/pcm_iec958.c
index 3b120adc..79d611d1 100644
--- a/src/pcm/pcm_iec958.c
+++ b/src/pcm/pcm_iec958.c
@@ -662,7 +662,7 @@ int _snd_pcm_iec958_open(snd_pcm_t **pcmp, const char *name,
 		SNDERR("invalid slave format");
 		return -EINVAL;
 	}
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	if (err < 0)
 		return err;
diff --git a/src/pcm/pcm_ladspa.c b/src/pcm/pcm_ladspa.c
index 03f31f76..d4432ae3 100644
--- a/src/pcm/pcm_ladspa.c
+++ b/src/pcm/pcm_ladspa.c
@@ -1782,7 +1782,7 @@ int _snd_pcm_ladspa_open(snd_pcm_t **pcmp, const char *name,
 	err = snd_pcm_slave_conf(root, slave, &sconf, 0);
 	if (err < 0)
 		return err;
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	if (err < 0)
 		return err;
diff --git a/src/pcm/pcm_lfloat.c b/src/pcm/pcm_lfloat.c
index d22277ba..7d946cbc 100644
--- a/src/pcm/pcm_lfloat.c
+++ b/src/pcm/pcm_lfloat.c
@@ -497,7 +497,7 @@ int _snd_pcm_lfloat_open(snd_pcm_t **pcmp, const char *name,
 		SNDERR("slave format is not linear integer or linear float");
 		return -EINVAL;
 	}
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	if (err < 0)
 		return err;
diff --git a/src/pcm/pcm_linear.c b/src/pcm/pcm_linear.c
index 43663787..6fc222cb 100644
--- a/src/pcm/pcm_linear.c
+++ b/src/pcm/pcm_linear.c
@@ -552,7 +552,7 @@ int _snd_pcm_linear_open(snd_pcm_t **pcmp, const char *name,
 		SNDERR("slave format is not linear");
 		return -EINVAL;
 	}
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	if (err < 0)
 		return err;
diff --git a/src/pcm/pcm_local.h b/src/pcm/pcm_local.h
index 24786392..e458b469 100644
--- a/src/pcm/pcm_local.h
+++ b/src/pcm/pcm_local.h
@@ -748,7 +748,7 @@ int snd_pcm_slave_conf(snd_config_t *root, snd_config_t *conf,
 
 int snd_pcm_open_slave(snd_pcm_t **pcmp, snd_config_t *root,
 		       snd_config_t *conf, snd_pcm_stream_t stream,
-		       int mode);
+		       int mode, snd_config_t *parent_conf);
 int snd_pcm_conf_generic_id(const char *id);
 
 int snd_pcm_hw_open_fd(snd_pcm_t **pcmp, const char *name, int fd, int mmap_emulation, int sync_ptr_ioctl);
diff --git a/src/pcm/pcm_meter.c b/src/pcm/pcm_meter.c
index 413b3cb4..b84747c4 100644
--- a/src/pcm/pcm_meter.c
+++ b/src/pcm/pcm_meter.c
@@ -779,7 +779,7 @@ int _snd_pcm_meter_open(snd_pcm_t **pcmp, const char *name,
 	err = snd_pcm_slave_conf(root, slave, &sconf, 0);
 	if (err < 0)
 		return err;
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	if (err < 0)
 		return err;
diff --git a/src/pcm/pcm_mulaw.c b/src/pcm/pcm_mulaw.c
index 87b3235e..389326b6 100644
--- a/src/pcm/pcm_mulaw.c
+++ b/src/pcm/pcm_mulaw.c
@@ -553,7 +553,7 @@ int _snd_pcm_mulaw_open(snd_pcm_t **pcmp, const char *name,
 		SNDERR("invalid slave format");
 		return -EINVAL;
 	}
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	if (err < 0)
 		return err;
diff --git a/src/pcm/pcm_multi.c b/src/pcm/pcm_multi.c
index c2ade361..9c492f95 100644
--- a/src/pcm/pcm_multi.c
+++ b/src/pcm/pcm_multi.c
@@ -1103,7 +1103,9 @@ int _snd_pcm_multi_open(snd_pcm_t **pcmp, const char *name,
 	}
 	
 	for (idx = 0; idx < slaves_count; ++idx) {
-		err = snd_pcm_open_slave(&slaves_pcm[idx], root, slaves_conf[idx], stream, mode);
+		err = snd_pcm_open_slave(&slaves_pcm[idx], root,
+					 slaves_conf[idx], stream, mode,
+					 conf);
 		if (err < 0)
 			goto _free;
 		snd_config_delete(slaves_conf[idx]);
diff --git a/src/pcm/pcm_plug.c b/src/pcm/pcm_plug.c
index 0f5264c6..ad3e6507 100644
--- a/src/pcm/pcm_plug.c
+++ b/src/pcm/pcm_plug.c
@@ -1215,7 +1215,7 @@ int _snd_pcm_plug_open(snd_pcm_t **pcmp, const char *name,
 	}
 #endif
 	
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	if (err < 0)
 		return err;
diff --git a/src/pcm/pcm_rate.c b/src/pcm/pcm_rate.c
index 28490ccc..f675a583 100644
--- a/src/pcm/pcm_rate.c
+++ b/src/pcm/pcm_rate.c
@@ -1532,7 +1532,7 @@ int _snd_pcm_rate_open(snd_pcm_t **pcmp, const char *name,
 		SNDERR("slave format is not linear");
 		return -EINVAL;
 	}
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	if (err < 0)
 		return err;
diff --git a/src/pcm/pcm_route.c b/src/pcm/pcm_route.c
index 09c1bd6f..daddf7c7 100644
--- a/src/pcm/pcm_route.c
+++ b/src/pcm/pcm_route.c
@@ -1152,7 +1152,7 @@ int _snd_pcm_route_open(snd_pcm_t **pcmp, const char *name,
 		return err;
 	}
 
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	if (err < 0) {
 		free(ttable);
diff --git a/src/pcm/pcm_softvol.c b/src/pcm/pcm_softvol.c
index 5c0413d8..d59d0315 100644
--- a/src/pcm/pcm_softvol.c
+++ b/src/pcm/pcm_softvol.c
@@ -814,7 +814,7 @@ int _snd_pcm_softvol_open(snd_pcm_t **pcmp, const char *name,
 		snd_config_delete(sconf);
 		return -EINVAL;
 	}
-	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
+	err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 	snd_config_delete(sconf);
 	if (err < 0)
 		return err;
diff --git a/src/rawmidi/rawmidi_virt.c b/src/rawmidi/rawmidi_virt.c
index 99c4be22..2cee7b34 100644
--- a/src/rawmidi/rawmidi_virt.c
+++ b/src/rawmidi/rawmidi_virt.c
@@ -53,6 +53,10 @@ typedef struct {
 	snd_seq_event_t out_event;
 	int pending;
 } snd_rawmidi_virtual_t;
+
+int _snd_seq_open_lconf(snd_seq_t **seqp, const char *name, 
+			int streams, int mode, snd_config_t *lconf,
+			snd_config_t *parent_conf);
 #endif
 
 static int snd_rawmidi_virtual_close(snd_rawmidi_t *rmidi)
@@ -439,7 +443,8 @@ int _snd_rawmidi_virtual_open(snd_rawmidi_t **inputp, snd_rawmidi_t **outputp,
 
 	if (! slave_str)
 		slave_str = "default";
-	err = snd_seq_open_lconf(&seq_handle, slave_str, streams, seq_mode, root);
+	err = _snd_seq_open_lconf(&seq_handle, slave_str, streams, seq_mode,
+				  root, conf);
 	if (err < 0)
 		return err;
 
diff --git a/src/seq/seq.c b/src/seq/seq.c
index 2ae83a7a..df7b64e6 100644
--- a/src/seq/seq.c
+++ b/src/seq/seq.c
@@ -919,7 +919,8 @@ static int snd_seq_open_conf(snd_seq_t **seqp, const char *name,
 }
 
 static int snd_seq_open_noupdate(snd_seq_t **seqp, snd_config_t *root,
-				 const char *name, int streams, int mode)
+				 const char *name, int streams, int mode,
+				 int hop)
 {
 	int err;
 	snd_config_t *seq_conf;
@@ -928,6 +929,7 @@ static int snd_seq_open_noupdate(snd_seq_t **seqp, snd_config_t *root,
 		SNDERR("Unknown SEQ %s", name);
 		return err;
 	}
+	snd_config_set_hop(seq_conf, hop);
 	err = snd_seq_open_conf(seqp, name, root, seq_conf, streams, mode);
 	snd_config_delete(seq_conf);
 	return err;
@@ -971,7 +973,7 @@ int snd_seq_open(snd_seq_t **seqp, const char *name,
 	err = snd_config_update();
 	if (err < 0)
 		return err;
-	return snd_seq_open_noupdate(seqp, snd_config, name, streams, mode);
+	return snd_seq_open_noupdate(seqp, snd_config, name, streams, mode, 0);
 }
 
 /**
@@ -993,9 +995,22 @@ int snd_seq_open_lconf(snd_seq_t **seqp, const char *name,
 		       int streams, int mode, snd_config_t *lconf)
 {
 	assert(seqp && name && lconf);
-	return snd_seq_open_noupdate(seqp, lconf, name, streams, mode);
+	return snd_seq_open_noupdate(seqp, lconf, name, streams, mode, 0);
 }
 
+#ifndef DOC_HIDDEN
+int _snd_seq_open_lconf(snd_seq_t **seqp, const char *name, 
+			int streams, int mode, snd_config_t *lconf,
+			snd_config_t *parent_conf)
+{
+	int hop;
+	assert(seqp && name && lconf);
+	if ((hop = snd_config_check_hop(parent_conf)) < 0)
+		return hop;
+	return snd_seq_open_noupdate(seqp, lconf, name, streams, mode, hop + 1);
+}
+#endif
+
 /**
  * \brief Close the sequencer
  * \param seq Handle returned from #snd_seq_open()
-- 
2.47.1