diff --git a/sys/netinet/sctp_crc32.c b/sys/netinet/sctp_crc32.c
index a36d36dc4861..97b881bb5062 100644
--- a/sys/netinet/sctp_crc32.c
+++ b/sys/netinet/sctp_crc32.c
@@ -1,148 +1,145 @@
 /*-
  * SPDX-License-Identifier: BSD-3-Clause
  *
  * Copyright (c) 2001-2007, by Cisco Systems, Inc. All rights reserved.
  * Copyright (c) 2008-2012, by Randall Stewart. All rights reserved.
  * Copyright (c) 2008-2012, by Michael Tuexen. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  * a) Redistributions of source code must retain the above copyright notice,
  *   this list of conditions and the following disclaimer.
  *
  * b) Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in
  *   the documentation and/or other materials provided with the distribution.
  *
  * c) Neither the name of Cisco Systems, Inc. nor the names of its
  *    contributors may be used to endorse or promote products derived
  *    from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  * THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include "opt_sctp.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/gsb_crc32.h>
 #include <sys/mbuf.h>
 
 #include <netinet/sctp.h>
 #include <netinet/sctp_crc32.h>
 #if defined(SCTP) || defined(SCTP_SUPPORT)
 #include <netinet/sctp_os.h>
 #include <netinet/sctp_pcb.h>
 #endif
 
 static uint32_t
 sctp_finalize_crc32c(uint32_t crc32c)
 {
 	uint32_t result;
 #if BYTE_ORDER == BIG_ENDIAN
 	uint8_t byte0, byte1, byte2, byte3;
 #endif
 
 	/* Complement the result */
 	result = ~crc32c;
 #if BYTE_ORDER == BIG_ENDIAN
 	/*
 	 * For BIG-ENDIAN platforms the result is in little-endian form. So
 	 * we must swap the bytes to return the result in network byte
 	 * order.
 	 */
 	byte0 = result & 0x000000ff;
 	byte1 = (result >> 8) & 0x000000ff;
 	byte2 = (result >> 16) & 0x000000ff;
 	byte3 = (result >> 24) & 0x000000ff;
 	crc32c = ((byte0 << 24) | (byte1 << 16) | (byte2 << 8) | byte3);
 #else
 	/*
 	 * For LITTLE ENDIAN platforms the result is in already in network
 	 * byte order.
 	 */
 	crc32c = result;
 #endif
 	return (crc32c);
 }
 
+static int
+sctp_calculate_cksum_cb(void *arg, void *data, u_int len)
+{
+	uint32_t *basep;
+
+	basep = arg;
+	*basep = calculate_crc32c(*basep, data, len);
+	return (0);
+}
+
 /*
  * Compute the SCTP checksum in network byte order for a given mbuf chain m
  * which contains an SCTP packet starting at offset.
  * Since this function is also called by ipfw, don't assume that
  * it is compiled on a kernel with SCTP support.
  */
 uint32_t
 sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
 {
-	uint32_t base = 0xffffffff;
-
-	while (offset > 0) {
-		KASSERT(m != NULL, ("sctp_calculate_cksum, offset > length of mbuf chain"));
-		if (offset < (uint32_t)m->m_len) {
-			break;
-		}
-		offset -= m->m_len;
-		m = m->m_next;
-	}
-	if (offset > 0) {
-		base = calculate_crc32c(base,
-		    (unsigned char *)(m->m_data + offset),
-		    (unsigned int)(m->m_len - offset));
-		m = m->m_next;
-	}
-	while (m != NULL) {
-		base = calculate_crc32c(base,
-		    (unsigned char *)m->m_data,
-		    (unsigned int)m->m_len);
-		m = m->m_next;
-	}
-	base = sctp_finalize_crc32c(base);
-	return (base);
+	uint32_t base;
+	int len;
+
+	M_ASSERTPKTHDR(m);
+	KASSERT(offset < m->m_pkthdr.len,
+	    ("%s: invalid offset %u into mbuf %p", __func__, offset, m));
+
+	base = 0xffffffff;
+	len = m->m_pkthdr.len - offset;
+	(void)m_apply(m, offset, len, sctp_calculate_cksum_cb, &base);
+	return (sctp_finalize_crc32c(base));
 }
 
 #if defined(SCTP) || defined(SCTP_SUPPORT)
 
 VNET_DEFINE(struct sctp_base_info, system_base_info);
 
 /*
  * Compute and insert the SCTP checksum in network byte order for a given
  * mbuf chain m which contains an SCTP packet starting at offset.
  */
 void
 sctp_delayed_cksum(struct mbuf *m, uint32_t offset)
 {
 	uint32_t checksum;
 
 	checksum = sctp_calculate_cksum(m, offset);
 	SCTP_STAT_DECR(sctps_sendhwcrc);
 	SCTP_STAT_INCR(sctps_sendswcrc);
 	offset += offsetof(struct sctphdr, checksum);
 
 	if (offset + sizeof(uint32_t) > (uint32_t)(m->m_pkthdr.len)) {
 #ifdef INVARIANTS
 		panic("sctp_delayed_cksum(): m->m_pkthdr.len: %d, offset: %u.",
 		    m->m_pkthdr.len, offset);
 #else
 		SCTP_PRINTF("sctp_delayed_cksum(): m->m_pkthdr.len: %d, offset: %u.\n",
 		    m->m_pkthdr.len, offset);
 #endif
 		return;
 	}
 	m_copyback(m, (int)offset, (int)sizeof(uint32_t), (caddr_t)&checksum);
 }
 #endif