diff --git a/sys/kern/uipc_sockbuf.c b/sys/kern/uipc_sockbuf.c
--- a/sys/kern/uipc_sockbuf.c
+++ b/sys/kern/uipc_sockbuf.c
@@ -44,6 +44,7 @@
 #include <sys/lock.h>
 #include <sys/malloc.h>
 #include <sys/mbuf.h>
+#include <sys/msan.h>
 #include <sys/mutex.h>
 #include <sys/proc.h>
 #include <sys/protosw.h>
@@ -908,6 +909,7 @@
 
 	if (m == NULL)
 		return;
+	kmsan_check_mbuf(m, "sbappend");
 	sbm_clrprotoflags(m, flags);
 	SBLASTRECORDCHK(sb);
 	n = sb->sb_mb;
@@ -1022,6 +1024,8 @@
 
 	KASSERT(m->m_nextpkt == NULL,("sbappendstream 0"));
 
+	kmsan_check_mbuf(m, "sbappend");
+
 #ifdef KERN_TLS
 	/*
 	 * Decrypted TLS records are appended as records via
@@ -1170,7 +1174,10 @@
 
 	if (m0 == NULL)
 		return;
+
+	kmsan_check_mbuf(m0, "sbappend");
 	m_clrprotoflags(m0);
+
 	/*
 	 * Put the first mbuf on the queue.  Note this permits zero length
 	 * records.
@@ -1207,6 +1214,12 @@
     struct mbuf *m0, struct mbuf *control, struct mbuf *ctrl_last)
 {
 	struct mbuf *m, *n, *nlast;
+
+	if (m0 != NULL)
+		kmsan_check_mbuf(m0, "sbappend");
+	if (control != NULL)
+		kmsan_check_mbuf(control, "sbappend");
+
 #if MSIZE <= 256
 	if (asa->sa_len > MLEN)
 		return (0);
@@ -1317,6 +1330,9 @@
 {
 	struct mbuf *m, *mlast;
 
+	kmsan_check_mbuf(m0, "sbappend");
+	kmsan_check_mbuf(control, "sbappend");
+
 	sbm_clrprotoflags(m0, flags);
 	m_last(control)->m_next = m0;