diff --git a/lib/libradius/radius.h b/lib/libradius/radius.h
index ac19d2b78..f49613368 100644
--- a/lib/libradius/radius.h
+++ b/lib/libradius/radius.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: radius.h,v 1.4 2024/02/25 06:22:45 yasuoka Exp $ */
+/*	$OpenBSD: radius.h,v 1.6 2024/06/29 07:19:18 yasuoka Exp $ */
 
 /*-
  * Copyright (c) 2009 Internet Initiative Japan Inc.
@@ -31,6 +31,7 @@
 
 #define RADIUS_DEFAULT_PORT		1812
 #define RADIUS_ACCT_DEFAULT_PORT	1813
+#define RADIUS_DAE_DEFAULT_PORT		3799
 
 /* RADIUS codes */
 #define RADIUS_CODE_ACCESS_REQUEST             1
@@ -42,6 +43,12 @@
 #define RADIUS_CODE_STATUS_SERVER             12
 #define RADIUS_CODE_STATUS_CLIENT             13
 
+#define RADIUS_CODE_DISCONNECT_REQUEST        40
+#define RADIUS_CODE_DISCONNECT_ACK            41
+#define RADIUS_CODE_DISCONNECT_NACK           42
+#define RADIUS_CODE_COA_REQUEST               43
+#define RADIUS_CODE_COA_ACK                   44
+#define RADIUS_CODE_COA_NACK                  45
 
 /* RADIUS attributes */
 #define RADIUS_TYPE_USER_NAME                  1
@@ -143,6 +150,9 @@
 #define RADIUS_TYPE_FRAMED_IPV6_ROUTE         99
 #define RADIUS_TYPE_FRAMED_IPV6_POOL         100
 
+/* RFC 5176 3.5. Error-Cause */
+#define RADIUS_TYPE_ERROR_CAUSE              101
+
 /* RFC 6911 3. Attributes */
 #define RADIUS_TYPE_FRAMED_IPV6_ADDRESS      168
 #define RADIUS_TYPE_DNS_SERVER_IPV6_ADDRESS  169
@@ -320,6 +330,42 @@
 #define RADIUS_TUNNEL_MEDIUM_TYPE_E163		7	/* E.163 (POTS) */
 #define RADIUS_TUNNEL_MEDIUM_TYPE_E164		8	/* E.164 (SMDS, Frame
 							 * Relay, ATM) */
+/* RFC 5167 3.5. Error-Cause */
+/* Residual Session Context Removed */
+#define RADIUS_ERROR_CAUSE_RESIDUAL_SESSION_REMOVED	201
+/* Invalid EAP Packet (Ignored) */
+#define RADIUS_ERROR_CAUSE_INVALID_EAP_PACKET		202
+/* Unsupported Attribute */
+#define RADIUS_ERROR_CAUSE_UNSUPPORTED_ATTRIBUTE	401
+/* Missing Attribute */
+#define RADIUS_ERROR_CAUSE_MISSING_ATTRIBUTE		402
+/* NAS Identification Mismatch */
+#define RADIUS_ERROR_CAUSE_NAS_IDENTIFICATION_MISMATCH	403
+/* Invalid Request */
+#define RADIUS_ERROR_CAUSE_INVALID_REQUEST		404
+/* Unsupported Service */
+#define RADIUS_ERROR_CAUSE_UNSUPPORTED_SERVICE		405
+/* Unsupported Extension */
+#define RADIUS_ERROR_CAUSE_UNSUPPORTED_EXTENSION	406
+/* Invalid Attribute Valu */
+#define RADIUS_ERROR_CAUSE_INVALID_ATTRIBUTE_VALUE	407
+/* Administratively Prohibited */
+#define RADIUS_ERROR_CAUSE_ADMINISTRATIVELY_PROHIBITED	501
+/* Request Not Routable (Proxy) */
+#define RADIUS_ERROR_CAUSE_REQUEST_NOT_ROUTABLE		502
+/* Session Context Not Found */
+#define RADIUS_ERROR_CAUSE_SESSION_NOT_FOUND		503
+/* Session Context Not Removable */
+#define RADIUS_ERROR_CAUSE_SESSION_NOT_REMOVABLE 	504
+/* Other Proxy Processing Error */
+#define RADIUS_ERROR_CAUSE_OTHER_PROXY_PROCESSING_ERROR	505
+/* Resources Unavailable */
+#define RADIUS_ERROR_CAUSE_RESOURCES_UNAVAILABLE	506
+/* Request Initiated */
+#define RADIUS_ERROR_CAUSE_REQUEST_INITIATED		507
+/* Multiple Session Selection Unsupported */
+#define RADIUS_ERROR_CAUSE_MULTI_SELECTION_UNSUPPORTED	508
+
 #include <sys/socket.h>
 #include <sys/cdefs.h>
 
diff --git a/lib/libssl/man/SSL_CTX_set_alpn_select_cb.3 b/lib/libssl/man/SSL_CTX_set_alpn_select_cb.3
index 683b6696e..5f8da325b 100644
--- a/lib/libssl/man/SSL_CTX_set_alpn_select_cb.3
+++ b/lib/libssl/man/SSL_CTX_set_alpn_select_cb.3
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: SSL_CTX_set_alpn_select_cb.3,v 1.8 2021/09/10 09:25:29 tb Exp $
+.\"	$OpenBSD: SSL_CTX_set_alpn_select_cb.3,v 1.9 2024/06/28 14:48:43 tb Exp $
 .\"	OpenSSL 87b81496 Apr 19 12:38:27 2017 -0400
 .\"	OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100
 .\"
@@ -49,7 +49,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 .\" OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: September 10 2021 $
+.Dd $Mdocdate: June 28 2024 $
 .Dt SSL_CTX_SET_ALPN_SELECT_CB 3
 .Os
 .Sh NAME
@@ -153,6 +153,15 @@ It implements the standard protocol selection.
 It is expected that this function is called from the application
 callback
 .Fa cb .
+If
+.Fn SSL_select_next_proto
+returns
+.Dv OPENSSL_NPN_NO_OVERLAP ,
+.Fa cb
+should ignore
+.Fa out
+and fail by returning
+.Dv SSL_TLSEXT_ERR_ALERT_FATAL .
 The protocol data in
 .Fa server ,
 .Fa server_len
@@ -175,7 +184,8 @@ value will point into either
 .Fa server
 or
 .Fa client ,
-so it should be copied immediately.
+so it must not be modified and
+should be copied immediately.
 If no match is found, the first item in
 .Fa client ,
 .Fa client_len
diff --git a/lib/libssl/ssl_lib.c b/lib/libssl/ssl_lib.c
index d1b552d94..f5d477e86 100644
--- a/lib/libssl/ssl_lib.c
+++ b/lib/libssl/ssl_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_lib.c,v 1.323 2024/04/15 16:00:05 tb Exp $ */
+/* $OpenBSD: ssl_lib.c,v 1.325 2024/06/29 07:34:12 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1785,45 +1785,70 @@ LSSL_ALIAS(SSL_get_servername_type);
  * It returns either:
  * OPENSSL_NPN_NEGOTIATED if a common protocol was found, or
  * OPENSSL_NPN_NO_OVERLAP if the fallback case was reached.
+ *
+ * XXX - the out argument points into server_list or client_list and should
+ * therefore really be const. We can't fix that without breaking the callers.
  */
 int
 SSL_select_next_proto(unsigned char **out, unsigned char *outlen,
-    const unsigned char *server, unsigned int server_len,
-    const unsigned char *client, unsigned int client_len)
+    const unsigned char *server_list, unsigned int server_list_len,
+    const unsigned char *client_list, unsigned int client_list_len)
 {
-	unsigned int		 i, j;
-	const unsigned char	*result;
-	int			 status = OPENSSL_NPN_UNSUPPORTED;
+	CBS client, client_proto, server, server_proto;
+
+	*out = NULL;
+	*outlen = 0;
+
+	/* First check that the client list is well-formed. */
+	CBS_init(&client, client_list, client_list_len);
+	if (!tlsext_alpn_check_format(&client))
+		goto err;
 
 	/*
-	 * For each protocol in server preference order,
-	 * see if we support it.
+	 * Use first client protocol as fallback. This is one way of doing NPN's
+	 * "opportunistic" protocol selection (see security considerations in
+	 * draft-agl-tls-nextprotoneg-04), and it is the documented behavior of
+	 * this API. For ALPN it's the callback's responsibility to fail on
+	 * OPENSSL_NPN_NO_OVERLAP.
 	 */
-	for (i = 0; i < server_len; ) {
-		for (j = 0; j < client_len; ) {
-			if (server[i] == client[j] &&
-			    memcmp(&server[i + 1],
-			    &client[j + 1], server[i]) == 0) {
-				/* We found a match */
-				result = &server[i];
-				status = OPENSSL_NPN_NEGOTIATED;
-				goto found;
+
+	if (!CBS_get_u8_length_prefixed(&client, &client_proto))
+		goto err;
+
+	*out = (unsigned char *)CBS_data(&client_proto);
+	*outlen = CBS_len(&client_proto);
+
+	/* Now check that the server list is well-formed. */
+	CBS_init(&server, server_list, server_list_len);
+	if (!tlsext_alpn_check_format(&server))
+		goto err;
+
+	/*
+	 * Walk the server list and select the first protocol that appears in
+	 * the client list.
+	 */
+	while (CBS_len(&server) > 0) {
+		if (!CBS_get_u8_length_prefixed(&server, &server_proto))
+			goto err;
+
+		CBS_init(&client, client_list, client_list_len);
+
+		while (CBS_len(&client) > 0) {
+			if (!CBS_get_u8_length_prefixed(&client, &client_proto))
+				goto err;
+
+			if (CBS_mem_equal(&client_proto,
+			    CBS_data(&server_proto), CBS_len(&server_proto))) {
+				*out = (unsigned char *)CBS_data(&server_proto);
+				*outlen = CBS_len(&server_proto);
+
+				return OPENSSL_NPN_NEGOTIATED;
 			}
-			j += client[j];
-			j++;
 		}
-		i += server[i];
-		i++;
 	}
 
-	/* There's no overlap between our protocols and the server's list. */
-	result = client;
-	status = OPENSSL_NPN_NO_OVERLAP;
-
- found:
-	*out = (unsigned char *) result + 1;
-	*outlen = result[0];
-	return (status);
+ err:
+	return OPENSSL_NPN_NO_OVERLAP;
 }
 LSSL_ALIAS(SSL_select_next_proto);
 
diff --git a/lib/libssl/ssl_packet.c b/lib/libssl/ssl_packet.c
index 70017b466..32d6cceb7 100644
--- a/lib/libssl/ssl_packet.c
+++ b/lib/libssl/ssl_packet.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_packet.c,v 1.15 2022/11/26 16:08:56 tb Exp $ */
+/* $OpenBSD: ssl_packet.c,v 1.16 2024/06/28 13:37:49 jsing Exp $ */
 /*
  * Copyright (c) 2016, 2017 Joel Sing <jsing@openbsd.org>
  *
@@ -18,34 +18,6 @@
 #include "bytestring.h"
 #include "ssl_local.h"
 
-static int
-ssl_is_sslv2_client_hello(CBS *header)
-{
-	uint16_t record_length;
-	uint8_t message_type;
-	CBS cbs;
-
-	CBS_dup(header, &cbs);
-
-	if (!CBS_get_u16(&cbs, &record_length) ||
-	    !CBS_get_u8(&cbs, &message_type))
-		return 0;
-
-	/*
-	 * The SSLv2 record length field uses variable length (2 or 3 byte)
-	 * encoding. Given the size of a client hello, we expect/require the
-	 * 2-byte form which is indicated by a one in the most significant bit.
-	 */
-	if ((record_length & 0x8000) == 0)
-		return 0;
-	if ((record_length & ~0x8000) < 3)
-		return 0;
-	if (message_type != SSL2_MT_CLIENT_HELLO)
-		return 0;
-
-	return 1;
-}
-
 static int
 ssl_is_sslv3_handshake(CBS *header)
 {
@@ -67,164 +39,6 @@ ssl_is_sslv3_handshake(CBS *header)
 	return 1;
 }
 
-static int
-ssl_convert_sslv2_client_hello(SSL *s)
-{
-	CBB cbb, handshake, client_hello, cipher_suites, compression, session_id;
-	CBS cbs, challenge, cipher_specs, session;
-	uint16_t record_length, client_version, cipher_specs_length;
-	uint16_t session_id_length, challenge_length;
-	unsigned char *client_random = NULL, *data = NULL;
-	size_t data_len, pad_len, len;
-	uint32_t cipher_spec;
-	uint8_t message_type;
-	unsigned char *pad;
-	int ret = -1;
-	int n;
-
-	memset(&cbb, 0, sizeof(cbb));
-
-	CBS_init(&cbs, s->packet, SSL3_RT_HEADER_LENGTH);
-
-	if (!CBS_get_u16(&cbs, &record_length) ||
-	    !CBS_get_u8(&cbs, &message_type) ||
-	    !CBS_get_u16(&cbs, &client_version))
-		return -1;
-
-	/*
-	 * The SSLv2 record length field uses variable length (2 or 3 byte)
-	 * encoding. Given the size of a client hello, we expect/require the
-	 * 2-byte form which is indicated by a one in the most significant bit.
-	 * Also note that the record length value does not include the bytes
-	 * used for the record length field.
-	 */
-	if ((record_length & 0x8000) == 0)
-		return -1;
-	record_length &= ~0x8000;
-	if (record_length < SSL3_RT_HEADER_LENGTH - 2)
-		return -1;
-	if (message_type != SSL2_MT_CLIENT_HELLO)
-		return -1;
-
-	if (record_length < 9) {
-		SSLerror(s, SSL_R_RECORD_LENGTH_MISMATCH);
-		return -1;
-	}
-	if (record_length > 4096) {
-		SSLerror(s, SSL_R_RECORD_TOO_LARGE);
-		return -1;
-	}
-
-	n = ssl3_packet_extend(s, record_length + 2);
-	if (n != record_length + 2)
-		return n;
-
-	tls1_transcript_record(s, s->packet + 2,
-	    s->packet_length - 2);
-	s->mac_packet = 0;
-
-	if (s->msg_callback)
-		s->msg_callback(0, SSL2_VERSION, 0,
-		    s->packet + 2, s->packet_length - 2, s,
-		    s->msg_callback_arg);
-
-	/* Decode the SSLv2 record containing the client hello. */
-	CBS_init(&cbs, s->packet, s->packet_length);
-
-	if (!CBS_get_u16(&cbs, &record_length))
-		return -1;
-	if (!CBS_get_u8(&cbs, &message_type))
-		return -1;
-	if (!CBS_get_u16(&cbs, &client_version))
-		return -1;
-	if (!CBS_get_u16(&cbs, &cipher_specs_length))
-		return -1;
-	if (!CBS_get_u16(&cbs, &session_id_length))
-		return -1;
-	if (!CBS_get_u16(&cbs, &challenge_length))
-		return -1;
-	if (!CBS_get_bytes(&cbs, &cipher_specs, cipher_specs_length))
-		return -1;
-	if (!CBS_get_bytes(&cbs, &session, session_id_length))
-		return -1;
-	if (!CBS_get_bytes(&cbs, &challenge, challenge_length))
-		return -1;
-	if (CBS_len(&cbs) != 0) {
-		SSLerror(s, SSL_R_RECORD_LENGTH_MISMATCH);
-		return -1;
-	}
-
-	/*
-	 * Convert SSLv2 challenge to SSLv3/TLS client random, by truncating or
-	 * left-padding with zero bytes.
-	 */
-	if ((client_random = malloc(SSL3_RANDOM_SIZE)) == NULL)
-		goto err;
-	if (!CBB_init_fixed(&cbb, client_random, SSL3_RANDOM_SIZE))
-		goto err;
-	if ((len = CBS_len(&challenge)) > SSL3_RANDOM_SIZE)
-		len = SSL3_RANDOM_SIZE;
-	pad_len = SSL3_RANDOM_SIZE - len;
-	if (!CBB_add_space(&cbb, &pad, pad_len))
-		goto err;
-	memset(pad, 0, pad_len);
-	if (!CBB_add_bytes(&cbb, CBS_data(&challenge), len))
-		goto err;
-	if (!CBB_finish(&cbb, NULL, NULL))
-		goto err;
-
-	/* Build SSLv3/TLS record with client hello. */
-	if (!CBB_init(&cbb, SSL3_RT_MAX_PLAIN_LENGTH))
-		goto err;
-	if (!CBB_add_u8(&cbb, SSL3_RT_HANDSHAKE))
-		goto err;
-	if (!CBB_add_u16(&cbb, 0x0301))
-		goto err;
-	if (!CBB_add_u16_length_prefixed(&cbb, &handshake))
-		goto err;
-	if (!CBB_add_u8(&handshake, SSL3_MT_CLIENT_HELLO))
-		goto err;
-	if (!CBB_add_u24_length_prefixed(&handshake, &client_hello))
-		goto err;
-	if (!CBB_add_u16(&client_hello, client_version))
-		goto err;
-	if (!CBB_add_bytes(&client_hello, client_random, SSL3_RANDOM_SIZE))
-		goto err;
-	if (!CBB_add_u8_length_prefixed(&client_hello, &session_id))
-		goto err;
-	if (!CBB_add_u16_length_prefixed(&client_hello, &cipher_suites))
-		goto err;
-	while (CBS_len(&cipher_specs) > 0) {
-		if (!CBS_get_u24(&cipher_specs, &cipher_spec))
-			goto err;
-		if ((cipher_spec & 0xff0000) != 0)
-			continue;
-		if (!CBB_add_u16(&cipher_suites, cipher_spec & 0xffff))
-			goto err;
-	}
-	if (!CBB_add_u8_length_prefixed(&client_hello, &compression))
-		goto err;
-	if (!CBB_add_u8(&compression, 0))
-		goto err;
-	if (!CBB_finish(&cbb, &data, &data_len))
-		goto err;
-
-	if (data_len > s->s3->rbuf.len)
-		goto err;
-
-	s->packet = s->s3->rbuf.buf;
-	s->packet_length = data_len;
-	memcpy(s->packet, data, data_len);
-	ret = 1;
-
- err:
-	CBB_cleanup(&cbb);
-	free(client_random);
-	free(data);
-
-	return (ret);
-}
-
 /*
  * Potentially do legacy processing on the first packet received by a TLS
  * server. We return 1 if we want SSLv3/TLS record processing to continue
@@ -233,7 +47,6 @@ ssl_convert_sslv2_client_hello(SSL *s)
 int
 ssl_server_legacy_first_packet(SSL *s)
 {
-	uint16_t min_version;
 	const char *data;
 	CBS header;
 
@@ -249,23 +62,6 @@ ssl_server_legacy_first_packet(SSL *s)
 	if (s->method->min_tls_version == s->method->max_tls_version)
 		return 1;
 
-	if (ssl_is_sslv2_client_hello(&header) == 1) {
-		/* Only permit SSLv2 client hellos if TLSv1.0 is enabled. */
-		if (ssl_enabled_tls_version_range(s, &min_version, NULL) != 1) {
-			SSLerror(s, SSL_R_NO_PROTOCOLS_AVAILABLE);
-			return -1;
-		}
-		if (min_version > TLS1_VERSION)
-			return 1;
-
-		if (ssl_convert_sslv2_client_hello(s) != 1) {
-			SSLerror(s, SSL_R_BAD_PACKET_LENGTH);
-			return -1;
-		}
-
-		return 1;
-	}
-
 	/* Ensure that we have SSL3_RT_HEADER_LENGTH (5 bytes) of the packet. */
 	if (CBS_len(&header) != SSL3_RT_HEADER_LENGTH) {
 		SSLerror(s, ERR_R_INTERNAL_ERROR);
diff --git a/regress/lib/libssl/unit/ssl_set_alpn_protos.c b/regress/lib/libssl/unit/ssl_set_alpn_protos.c
index 87dd4d9e5..6f3fcfbc2 100644
--- a/regress/lib/libssl/unit/ssl_set_alpn_protos.c
+++ b/regress/lib/libssl/unit/ssl_set_alpn_protos.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ssl_set_alpn_protos.c,v 1.2 2022/07/21 03:59:04 tb Exp $ */
+/*	$OpenBSD: ssl_set_alpn_protos.c,v 1.3 2024/06/28 14:50:37 tb Exp $ */
 /*
  * Copyright (c) 2022 Theo Buehler <tb@openbsd.org>
  *
@@ -20,6 +20,21 @@
 
 #include <openssl/ssl.h>
 
+static void
+hexdump(const unsigned char *buf, size_t len)
+{
+	size_t i;
+
+	if (buf == NULL) {
+		fprintf(stderr, "(null), len %zu\n", len);
+		return;
+	}
+	for (i = 1; i <= len; i++)
+		fprintf(stderr, " 0x%02hhx,%s", buf[i - 1], i % 8 ? "" : "\n");
+	if (len % 8)
+		fprintf(stderr, "\n");
+}
+
 struct alpn_test {
 	const char *description;
 	const uint8_t protocols[24];
@@ -186,6 +201,279 @@ test_ssl_set_alpn_protos_edge_cases(void)
 	return failed;
 }
 
+static const struct select_next_proto_test {
+	const unsigned char *server_list;
+	size_t server_list_len;
+	const unsigned char *client_list;
+	size_t client_list_len;
+	int want_ret;
+	const unsigned char *want_out;
+	unsigned char want_out_len; /* yes, unsigned char */
+} select_next_proto_tests[] = {
+	{
+		.server_list = "\x01" "a" "\x01" "b" "\x01" "c",
+		.server_list_len = 6,
+		.client_list = "\x01" "a",
+		.client_list_len = 2,
+		.want_ret = OPENSSL_NPN_NEGOTIATED,
+		.want_out = "a",
+		.want_out_len = 1,
+	},
+	{
+		.server_list = "\x01" "a" "\x01" "b" "\x01" "c",
+		.server_list_len = 6,
+		.client_list = "\x02" "aa" "\x01" "b" "\x01" "c",
+		.client_list_len = 7,
+		.want_ret = OPENSSL_NPN_NEGOTIATED,
+		.want_out = "b",
+		.want_out_len = 1,
+	},
+	{
+		/* Use server preference. */
+		.server_list = "\x01" "a" "\x01" "b" "\x01" "c",
+		.server_list_len = 6,
+		.client_list = "\x01" "c" "\x01" "b" "\x01" "a",
+		.client_list_len = 6,
+		.want_ret = OPENSSL_NPN_NEGOTIATED,
+		.want_out = "a",
+		.want_out_len = 1,
+	},
+	{
+		/* Again server preference wins. */
+		.server_list = "\x01" "a" "\x03" "bbb" "\x02" "cc",
+		.server_list_len = 9,
+		.client_list = "\x01" "z" "\x02" "cc" "\x03" "bbb",
+		.client_list_len = 9,
+		.want_ret = OPENSSL_NPN_NEGOTIATED,
+		.want_out = "bbb",
+		.want_out_len = 3,
+	},
+	{
+		/* No overlap fails with first client protocol. */
+		.server_list = "\x01" "a" "\x01" "b" "\x01" "c",
+		.server_list_len = 6,
+		.client_list = "\x01" "z" "\x01" "y",
+		.client_list_len = 4,
+		.want_ret = OPENSSL_NPN_NO_OVERLAP,
+		.want_out = "z",
+		.want_out_len = 1,
+	},
+	{
+		/*
+		 * No server protocols is a misconfiguration, but should fail
+		 * cleanly.
+		 */
+		.server_list = "",
+		.server_list_len = 0,
+		.client_list = "\x01" "a" "\x01" "b" "\x01" "c",
+		.client_list_len = 6,
+		.want_out = "a",
+		.want_out_len = 1,
+		.want_ret = OPENSSL_NPN_NO_OVERLAP,
+	},
+	{
+		/*
+		 * NULL server protocols is a programming error that fails
+		 * cleanly.
+		 */
+		.server_list = NULL,
+		.server_list_len = 0,
+		.client_list = "\x01" "a" "\x01" "b" "\x01" "c",
+		.client_list_len = 6,
+		.want_out = "a",
+		.want_out_len = 1,
+		.want_ret = OPENSSL_NPN_NO_OVERLAP,
+	},
+	{
+		/*
+		 * Malformed server protocols is a misconfiguration, but it
+		 * should fail cleanly.
+		 */
+		.server_list = "\x00",
+		.server_list_len = 1,
+		.client_list = "\x01" "a" "\x01" "b" "\x01" "c",
+		.client_list_len = 6,
+		.want_out = "a",
+		.want_out_len = 1,
+		.want_ret = OPENSSL_NPN_NO_OVERLAP,
+	},
+	{
+		/*
+		 * Malformed server protocols is a misconfiguration, but it
+		 * should fail cleanly.
+		 */
+		.server_list = "\x01" "a" "\x03" "bb",
+		.server_list_len = 5,
+		.client_list = "\x01" "a" "\x01" "b" "\x01" "c",
+		.client_list_len = 6,
+		.want_out = "a",
+		.want_out_len = 1,
+		.want_ret = OPENSSL_NPN_NO_OVERLAP,
+	},
+	{
+		/*
+		 * Empty client protocols is not reachable from the ALPN
+		 * callback. It fails cleanly with NULL protocol and 0 length.
+		 */
+		.server_list = "\x01" "a",
+		.server_list_len = 2,
+		.client_list = "",
+		.client_list_len = 0,
+		.want_out = NULL,
+		.want_out_len = 0,
+		.want_ret = OPENSSL_NPN_NO_OVERLAP,
+	},
+	{
+		/*
+		 * NULL client protocols is not reachable from the ALPN
+		 * callback. It fails cleanly with NULL protocol and 0 length.
+		 */
+		.server_list = "\x01" "a",
+		.server_list_len = 2,
+		.client_list = NULL,
+		.client_list_len = 0,
+		.want_out = NULL,
+		.want_out_len = 0,
+		.want_ret = OPENSSL_NPN_NO_OVERLAP,
+	},
+	{
+		/*
+		 * Malformed client list fails cleanly with NULL protocol and
+		 * 0 length.
+		 */
+		.server_list = "\x01" "a",
+		.server_list_len = 2,
+		.client_list = "\x01" "a" "\x02" "bb" "\x03" "cc" "\x04" "ddd",
+		.client_list_len = 12,
+		.want_out = NULL,
+		.want_out_len = 0,
+		.want_ret = OPENSSL_NPN_NO_OVERLAP,
+	},
+	{
+		/*
+		 * Malformed client list fails cleanly with NULL protocol and
+		 * 0 length.
+		 */
+		.server_list = "\x01" "a",
+		.server_list_len = 2,
+		.client_list = "\x01" "a" "\x02" "bb" "\x00" "\x03" "ddd",
+		.client_list_len = 10,
+		.want_out = NULL,
+		.want_out_len = 0,
+		.want_ret = OPENSSL_NPN_NO_OVERLAP,
+	},
+
+	/*
+	 * Some non-toy examples.
+	 */
+
+	{
+		.server_list = "\x08" "http/1.1" "\x06" "spdy/1",
+		.server_list_len = 16,
+		.client_list = "\x08" "http/2.0" "\x08" "http/1.1",
+		.client_list_len = 18,
+		.want_out = "http/1.1",
+		.want_out_len = 8,
+		.want_ret = OPENSSL_NPN_NEGOTIATED,
+	},
+	{
+		.server_list = "\x08" "http/2.0" "\x06" "spdy/1",
+		.server_list_len = 16,
+		.client_list = "\x08" "http/1.0" "\x08" "http/1.1",
+		.client_list_len = 18,
+		.want_out = "http/1.0",
+		.want_out_len = 8,
+		.want_ret = OPENSSL_NPN_NO_OVERLAP,
+	},
+	{
+		.server_list = "\x08" "http/1.1" "\x08" "http/1.0",
+		.server_list_len = 18,
+		.client_list = "\x08" "http/1.0" "\x08" "http/1.1",
+		.client_list_len = 18,
+		.want_out = "http/1.1",
+		.want_out_len = 8,
+		.want_ret = OPENSSL_NPN_NEGOTIATED,
+	},
+	{
+		/* Server malformed. */
+		.server_list = "\x08" "http/1.1" "\x07" "http/1.0",
+		.server_list_len = 18,
+		.client_list = "\x08" "http/1.0" "\x08" "http/1.1",
+		.client_list_len = 18,
+		.want_out = "http/1.0",
+		.want_out_len = 8,
+		.want_ret = OPENSSL_NPN_NO_OVERLAP,
+	},
+	{
+		/* Server malformed. */
+		.server_list = "\x07" "http/1.1" "\x08" "http/1.0",
+		.server_list_len = 18,
+		.client_list = "\x08" "http/1.0" "\x08" "http/1.1",
+		.client_list_len = 18,
+		.want_out = "http/1.0",
+		.want_out_len = 8,
+		.want_ret = OPENSSL_NPN_NO_OVERLAP,
+	},
+	{
+		/* Client has trailing bytes. */
+		.server_list = "\x08" "http/1.1" "\x08" "http/1.0",
+		.server_list_len = 18,
+		.client_list = "\x08" "http/1.0" "\x07" "http/1.1",
+		.client_list_len = 18,
+		.want_out = NULL,
+		.want_out_len = 0,
+		.want_ret = OPENSSL_NPN_NO_OVERLAP,
+	},
+};
+
+#define N_SELECT_NEXT_PROTO_TESTS \
+    (sizeof(select_next_proto_tests) / sizeof(select_next_proto_tests[0]))
+
+static int
+select_next_proto_testcase(const struct select_next_proto_test *test)
+{
+	unsigned char *out;
+	unsigned char out_len;
+	int ret;
+	int failed = 0;
+
+	ret = SSL_select_next_proto(&out, &out_len, test->server_list,
+	    test->server_list_len, test->client_list, test->client_list_len);
+
+	if (ret != test->want_ret || out_len != test->want_out_len ||
+	    (out == NULL && test->want_out != NULL) ||
+	    (out != NULL && test->want_out == NULL) ||
+	    (out != NULL && test->want_out != NULL &&
+	     memcmp(out, test->want_out, out_len) != 0)) {
+		fprintf(stderr, "FAIL: ret: %u (want %u), out_len: %u (want %u)\n",
+		    ret, test->want_ret, out_len, test->want_out_len);
+		fprintf(stderr, "\ngot:\n");
+		hexdump(out, out_len);
+		fprintf(stderr, "\nwant:\n");
+		hexdump(test->want_out, test->want_out_len);
+		fprintf(stderr, "\nserver:\n");
+		hexdump(test->server_list, test->server_list_len);
+		fprintf(stderr, "\nclient:\n");
+		hexdump(test->client_list, test->client_list_len);
+		fprintf(stderr, "\n");
+		failed = 1;
+	}
+
+	return failed;
+}
+
+static int
+test_ssl_select_next_proto(void)
+{
+	size_t i;
+	int failed = 0;
+
+	for (i = 0; i < N_SELECT_NEXT_PROTO_TESTS; i++)
+		failed |= select_next_proto_testcase(&select_next_proto_tests[i]);
+
+	return failed;
+}
+
 int
 main(void)
 {
@@ -197,6 +485,8 @@ main(void)
 
 	failed |= test_ssl_set_alpn_protos_edge_cases();
 
+	failed |= test_ssl_select_next_proto();
+
 	if (!failed)
 		printf("PASS %s\n", __FILE__);
 
diff --git a/regress/sys/kern/Makefile b/regress/sys/kern/Makefile
index f2f4ddc67..a75bf1e46 100644
--- a/regress/sys/kern/Makefile
+++ b/regress/sys/kern/Makefile
@@ -1,4 +1,4 @@
-#	$OpenBSD: Makefile,v 1.105 2023/07/06 07:45:56 deraadt Exp $
+#	$OpenBSD: Makefile,v 1.106 2024/06/28 21:36:05 bluhm Exp $
 
 SUBDIR+= accept access
 SUBDIR+= bind
@@ -22,7 +22,7 @@ SUBDIR+= setuid
 .endif
 SUBDIR+= signal sosplice stackjmp stackpivot syscall_segment
 SUBDIR+= sysvmsg sysvsem sysvshm
-SUBDIR+= unalign unfdpass unixsockets unveil unveil-unmount
+SUBDIR+= unalign unfdpass unixsockets unp-write-closed unveil unveil-unmount
 SUBDIR+= wait
 SUBDIR+= xonly
 
diff --git a/regress/sys/kern/unp-write-closed/Makefile b/regress/sys/kern/unp-write-closed/Makefile
new file mode 100644
index 000000000..832994174
--- /dev/null
+++ b/regress/sys/kern/unp-write-closed/Makefile
@@ -0,0 +1,5 @@
+#	$OpenBSD: Makefile,v 1.1.1.1 2024/06/28 21:07:27 bluhm Exp $
+
+PROG=	unp-write-closed
+
+.include <bsd.regress.mk>
diff --git a/regress/sys/kern/unp-write-closed/unp-write-closed.c b/regress/sys/kern/unp-write-closed/unp-write-closed.c
new file mode 100644
index 000000000..51e84ec7c
--- /dev/null
+++ b/regress/sys/kern/unp-write-closed/unp-write-closed.c
@@ -0,0 +1,83 @@
+/*	$OpenBSD: unp-write-closed.c,v 1.1.1.1 2024/06/28 21:07:27 bluhm Exp $	*/
+/*
+ * Copyright (c) 2024 Vitaliy Makkoveev <mvs@openbsd.org>
+ * Copyright (c) 2024 Alenander Bluhm <bluhm@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+
+#include <err.h>
+#include <errno.h>
+#include <signal.h>
+#include <unistd.h>
+
+sig_atomic_t done = 0;
+
+void
+handler(int sigraised)
+{
+	done = 1;
+}
+
+int
+main(int argc, char *argv[])
+{
+	int i, s[2], status;
+	pid_t pid;
+
+	if (signal(SIGPIPE, SIG_IGN) == SIG_ERR)
+		err(1, "signal pipe");
+	if (signal(SIGALRM, handler) == SIG_ERR)
+		err(1, "signal alrm");
+	alarm(30);
+
+	while (!done) {
+		if (socketpair(AF_UNIX, SOCK_STREAM, 0, s) < 0)
+			err(1, "socketpair");
+
+		switch ((pid = fork())) {
+		case -1:
+			err(1, "fork");
+		case 0:
+			if (close(s[0]) < 0)
+				err(1, "child close 0");
+			if (close(s[1]) < 0)
+				err(1, "child close 1");
+			return 0;
+		default:
+			if (close(s[1]) < 0)
+				err(1, "parent close 1");
+			for (i = 1000000; i > 0; i--) {
+				if (write(s[0], "1", 1) < 0)
+					break;
+			}
+			if (i <= 0)
+				errx(1, "write did not fail");
+			if (errno != EPIPE)
+				err(1, "write");
+			if (close(s[0]) < 0)
+				err(1, "parent close 1");
+			if (waitpid(pid, &status, 0) < 0)
+				err(1, "waitpid");
+			if (status != 0)
+				errx(1, "child status %d", status);
+			break;
+		}
+	}
+
+	return 0;
+}
diff --git a/sys/dev/pci/drm/amd/pm/legacy-dpm/amdgpu_kv_dpm.c b/sys/dev/pci/drm/amd/pm/legacy-dpm/amdgpu_kv_dpm.c
index 5cb4725c7..c8586cb7d 100644
--- a/sys/dev/pci/drm/amd/pm/legacy-dpm/amdgpu_kv_dpm.c
+++ b/sys/dev/pci/drm/amd/pm/legacy-dpm/amdgpu_kv_dpm.c
@@ -164,6 +164,8 @@ static void sumo_construct_vid_mapping_table(struct amdgpu_device *adev,
 
 	for (i = 0; i < SUMO_MAX_HARDWARE_POWERLEVELS; i++) {
 		if (table[i].ulSupportedSCLK != 0) {
+			if (table[i].usVoltageIndex >= SUMO_MAX_NUMBER_VOLTAGES)
+				continue;
 			vid_mapping_table->entries[table[i].usVoltageIndex].vid_7bit =
 				table[i].usVoltageID;
 			vid_mapping_table->entries[table[i].usVoltageIndex].vid_2bit =
diff --git a/sys/dev/pci/drm/i915/display/intel_dp.c b/sys/dev/pci/drm/i915/display/intel_dp.c
index f32ec5ca3..f80bd9f03 100644
--- a/sys/dev/pci/drm/i915/display/intel_dp.c
+++ b/sys/dev/pci/drm/i915/display/intel_dp.c
@@ -393,6 +393,10 @@ bool intel_dp_can_bigjoiner(struct intel_dp *intel_dp)
 	struct intel_encoder *encoder = &intel_dig_port->base;
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 
+	/* eDP MSO is not compatible with joiner */
+	if (intel_dp->mso_link_count)
+		return false;
+
 	return DISPLAY_VER(dev_priv) >= 12 ||
 		(DISPLAY_VER(dev_priv) == 11 &&
 		 encoder->port != PORT_A);
diff --git a/sys/dev/pci/drm/radeon/sumo_dpm.c b/sys/dev/pci/drm/radeon/sumo_dpm.c
index d49c145db..f7f1ddc6c 100644
--- a/sys/dev/pci/drm/radeon/sumo_dpm.c
+++ b/sys/dev/pci/drm/radeon/sumo_dpm.c
@@ -1621,6 +1621,8 @@ void sumo_construct_vid_mapping_table(struct radeon_device *rdev,
 
 	for (i = 0; i < SUMO_MAX_HARDWARE_POWERLEVELS; i++) {
 		if (table[i].ulSupportedSCLK != 0) {
+			if (table[i].usVoltageIndex >= SUMO_MAX_NUMBER_VOLTAGES)
+				continue;
 			vid_mapping_table->entries[table[i].usVoltageIndex].vid_7bit =
 				table[i].usVoltageID;
 			vid_mapping_table->entries[table[i].usVoltageIndex].vid_2bit =
diff --git a/sys/dev/pv/if_vio.c b/sys/dev/pv/if_vio.c
index f216b83cd..5ff0ccac6 100644
--- a/sys/dev/pv/if_vio.c
+++ b/sys/dev/pv/if_vio.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_vio.c,v 1.41 2024/06/26 01:40:49 jsg Exp $	*/
+/*	$OpenBSD: if_vio.c,v 1.42 2024/06/28 14:46:31 jan Exp $	*/
 
 /*
  * Copyright (c) 2012 Stefan Fritsch, Alexander Fiveg.
@@ -419,7 +419,7 @@ vio_alloc_mem(struct vio_softc *sc)
 	 */
 	allocsize = sizeof(struct virtio_net_hdr) * txqsize;
 
-	if (vsc->sc_nvqs == 3) {
+	if (virtio_has_feature(vsc, VIRTIO_NET_F_CTRL_VQ)) {
 		allocsize += sizeof(struct virtio_net_ctrl_cmd) * 1;
 		allocsize += sizeof(struct virtio_net_ctrl_status) * 1;
 		allocsize += sizeof(struct virtio_net_ctrl_rx) * 1;
@@ -436,7 +436,7 @@ vio_alloc_mem(struct vio_softc *sc)
 	kva = sc->sc_dma_kva;
 	sc->sc_tx_hdrs = (struct virtio_net_hdr*)(kva + offset);
 	offset += sizeof(struct virtio_net_hdr) * txqsize;
-	if (vsc->sc_nvqs == 3) {
+	if (virtio_has_feature(vsc, VIRTIO_NET_F_CTRL_VQ)) {
 		sc->sc_ctrl_cmd = (void*)(kva + offset);
 		offset += sizeof(*sc->sc_ctrl_cmd);
 		sc->sc_ctrl_status = (void*)(kva + offset);
@@ -529,7 +529,7 @@ vio_needs_reset(struct vio_softc *sc)
 {
 	if (virtio_get_status(sc->sc_virtio) &
 	    VIRTIO_CONFIG_DEVICE_STATUS_DEVICE_NEEDS_RESET) {
-		printf("%s: device needs reset", sc->sc_dev.dv_xname);
+		printf("%s: device needs reset\n", sc->sc_dev.dv_xname);
 		vio_ctrl_wakeup(sc, RESET);
 		return 1;
 	}
@@ -604,8 +604,7 @@ vio_attach(struct device *parent, struct device *self, void *aux)
 		virtio_postpone_intr_far(&sc->sc_vq[VQTX]);
 	else
 		virtio_stop_vq_intr(vsc, &sc->sc_vq[VQTX]);
-	if (virtio_has_feature(vsc, VIRTIO_NET_F_CTRL_VQ) &&
-	    virtio_has_feature(vsc, VIRTIO_NET_F_CTRL_RX)) {
+	if (virtio_has_feature(vsc, VIRTIO_NET_F_CTRL_VQ)) {
 		if (virtio_alloc_vq(vsc, &sc->sc_vq[VQCTL], 2, NBPG, 1,
 		    "control") == 0) {
 			sc->sc_vq[VQCTL].vq_done = vio_ctrleof;
@@ -760,7 +759,7 @@ vio_stop(struct ifnet *ifp, int disable)
 	/* only way to stop I/O and DMA is resetting... */
 	virtio_reset(vsc);
 	vio_rxeof(sc);
-	if (vsc->sc_nvqs >= 3)
+	if (virtio_has_feature(vsc, VIRTIO_NET_F_CTRL_VQ))
 		vio_ctrl_wakeup(sc, RESET);
 	vio_tx_drain(sc);
 	if (disable)
@@ -769,10 +768,10 @@ vio_stop(struct ifnet *ifp, int disable)
 	virtio_reinit_start(vsc);
 	virtio_start_vq_intr(vsc, &sc->sc_vq[VQRX]);
 	virtio_stop_vq_intr(vsc, &sc->sc_vq[VQTX]);
-	if (vsc->sc_nvqs >= 3)
+	if (virtio_has_feature(vsc, VIRTIO_NET_F_CTRL_VQ))
 		virtio_start_vq_intr(vsc, &sc->sc_vq[VQCTL]);
 	virtio_reinit_end(vsc);
-	if (vsc->sc_nvqs >= 3)
+	if (virtio_has_feature(vsc, VIRTIO_NET_F_CTRL_VQ))
 		vio_ctrl_wakeup(sc, FREE);
 }
 
@@ -959,7 +958,7 @@ vio_dump(struct vio_softc *sc)
 	printf("rx tick active: %d\n", !timeout_triggered(&sc->sc_rxtick));
 	printf("RX virtqueue:\n");
 	virtio_vq_dump(&vsc->sc_vqs[VQRX]);
-	if (vsc->sc_nvqs == 3) {
+	if (virtio_has_feature(vsc, VIRTIO_NET_F_CTRL_VQ)) {
 		printf("CTL virtqueue:\n");
 		virtio_vq_dump(&vsc->sc_vqs[VQCTL]);
 		printf("ctrl_inuse: %d\n", sc->sc_ctrl_inuse);
@@ -1530,7 +1529,7 @@ vio_wait_ctrl_done(struct vio_softc *sc)
 		r = tsleep_nsec(&sc->sc_ctrl_inuse, PRIBIO, "viodone",
 		    VIRTIO_NET_CTRL_TIMEOUT);
 		if (r == EWOULDBLOCK) {
-			printf("%s: ctrl queue timeout", sc->sc_dev.dv_xname);
+			printf("%s: ctrl queue timeout\n", sc->sc_dev.dv_xname);
 			vio_ctrl_wakeup(sc, RESET);
 			return ENXIO;
 		}
@@ -1648,7 +1647,7 @@ vio_iff(struct vio_softc *sc)
 
 	ifp->if_flags &= ~IFF_ALLMULTI;
 
-	if (vsc->sc_nvqs < 3) {
+	if (!virtio_has_feature(vsc, VIRTIO_NET_F_CTRL_RX)) {
 		/* no ctrl vq; always promisc */
 		ifp->if_flags |= IFF_ALLMULTI | IFF_PROMISC;
 		return;
@@ -1682,9 +1681,6 @@ vio_iff(struct vio_softc *sc)
 
 	sc->sc_ctrl_mac_tbl_mc->nentries = rxfilter ? nentries : 0;
 
-	if (vsc->sc_nvqs < 3)
-		return;
-
 	r = vio_set_rx_filter(sc);
 	if (r == EIO)
 		allmulti = 1; /* fallback */
diff --git a/sys/kern/uipc_socket2.c b/sys/kern/uipc_socket2.c
index df5086c86..27edd54af 100644
--- a/sys/kern/uipc_socket2.c
+++ b/sys/kern/uipc_socket2.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uipc_socket2.c,v 1.155 2024/05/17 19:11:14 mvs Exp $	*/
+/*	$OpenBSD: uipc_socket2.c,v 1.156 2024/06/28 21:30:24 mvs Exp $	*/
 /*	$NetBSD: uipc_socket2.c,v 1.11 1996/02/04 02:17:55 christos Exp $	*/
 
 /*
@@ -160,8 +160,6 @@ void
 soisdisconnected(struct socket *so)
 {
 	soassertlocked(so);
-	so->so_state &= ~(SS_ISCONNECTING|SS_ISCONNECTED|SS_ISDISCONNECTING);
-	so->so_state |= SS_ISDISCONNECTED;
 
 	mtx_enter(&so->so_rcv.sb_mtx);
 	so->so_rcv.sb_state |= SS_CANTRCVMORE;
@@ -171,6 +169,9 @@ soisdisconnected(struct socket *so)
 	so->so_snd.sb_state |= SS_CANTSENDMORE;
 	mtx_leave(&so->so_snd.sb_mtx);
 
+	so->so_state &= ~(SS_ISCONNECTING|SS_ISCONNECTED|SS_ISDISCONNECTING);
+	so->so_state |= SS_ISDISCONNECTED;
+
 	wakeup(&so->so_timeo);
 	sowwakeup(so);
 	sorwakeup(so);
diff --git a/sys/kern/uipc_usrreq.c b/sys/kern/uipc_usrreq.c
index fee5d29ab..580698ca8 100644
--- a/sys/kern/uipc_usrreq.c
+++ b/sys/kern/uipc_usrreq.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uipc_usrreq.c,v 1.207 2024/06/26 12:23:36 mvs Exp $	*/
+/*	$OpenBSD: uipc_usrreq.c,v 1.208 2024/06/28 21:30:24 mvs Exp $	*/
 /*	$NetBSD: uipc_usrreq.c,v 1.18 1996/02/09 19:00:50 christos Exp $	*/
 
 /*
@@ -513,6 +513,14 @@ uipc_send(struct socket *so, struct mbuf *m, struct mbuf *nam,
 			goto out;
 	}
 
+	/*
+	 * We hold both solock() and `sb_mtx' mutex while modifying
+	 * SS_CANTSENDMORE flag. solock() is enough to check it.
+	 */
+	if (so->so_snd.sb_state & SS_CANTSENDMORE) {
+		error = EPIPE;
+		goto dispose;
+	}
 	if (unp->unp_conn == NULL) {
 		error = ENOTCONN;
 		goto dispose;
@@ -531,12 +539,6 @@ uipc_send(struct socket *so, struct mbuf *m, struct mbuf *nam,
 	 */
 	mtx_enter(&so2->so_rcv.sb_mtx);
 	mtx_enter(&so->so_snd.sb_mtx);
-	if (so->so_snd.sb_state & SS_CANTSENDMORE) {
-		mtx_leave(&so->so_snd.sb_mtx);
-		mtx_leave(&so2->so_rcv.sb_mtx);
-		error = EPIPE;
-		goto dispose;
-	}
 	if (control) {
 		if (sbappendcontrol(so2, &so2->so_rcv, m, control)) {
 			control = NULL;
diff --git a/sys/miscfs/fifofs/fifo_vnops.c b/sys/miscfs/fifofs/fifo_vnops.c
index 97b14c1bf..aa04381db 100644
--- a/sys/miscfs/fifofs/fifo_vnops.c
+++ b/sys/miscfs/fifofs/fifo_vnops.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: fifo_vnops.c,v 1.105 2024/05/03 17:43:09 mvs Exp $	*/
+/*	$OpenBSD: fifo_vnops.c,v 1.106 2024/06/28 21:30:24 mvs Exp $	*/
 /*	$NetBSD: fifo_vnops.c,v 1.18 1996/03/16 23:52:42 christos Exp $	*/
 
 /*
@@ -174,10 +174,16 @@ fifo_open(void *v)
 			return (error);
 		}
 		fip->fi_readers = fip->fi_writers = 0;
+		/*
+		 * Should take both solock() and `sb_mtx' mutex for
+		 * SS_CANTSENDMORE flag modifications.
+		 */
+		solock(wso);
 		mtx_enter(&wso->so_snd.sb_mtx);
 		wso->so_snd.sb_state |= SS_CANTSENDMORE;
 		wso->so_snd.sb_lowat = PIPE_BUF;
 		mtx_leave(&wso->so_snd.sb_mtx);
+		sounlock(wso);
 	} else {
 		rso = fip->fi_readsock;
 		wso = fip->fi_writesock;
@@ -185,9 +191,11 @@ fifo_open(void *v)
 	if (ap->a_mode & FREAD) {
 		fip->fi_readers++;
 		if (fip->fi_readers == 1) {
+			solock(wso);
 			mtx_enter(&wso->so_snd.sb_mtx);
 			wso->so_snd.sb_state &= ~SS_CANTSENDMORE;
 			mtx_leave(&wso->so_snd.sb_mtx);
+			sounlock(wso);
 			if (fip->fi_writers > 0)
 				wakeup(&fip->fi_writers);
 		}