diff --git a/common/cli.c b/common/cli.c
index bcc7264d51a..87ce0e4d144 100644
--- a/common/cli.c
+++ b/common/cli.c
@@ -138,11 +138,9 @@ int run_command_list(const char *cmd, int len, int flag)
 #endif
 	}
 	if (need_buff) {
-		buff = malloc(len + 1);
+		buff = memdup_nul(cmd, len);
 		if (!buff)
 			return 1;
-		memcpy(buff, cmd, len);
-		buff[len] = '\0';
 	}
 #ifdef CONFIG_HUSH_PARSER
 	if (use_hush_old()) {
diff --git a/common/stdio.c b/common/stdio.c
index fc965944209..038e576147b 100644
--- a/common/stdio.c
+++ b/common/stdio.c
@@ -217,27 +217,11 @@ struct stdio_dev *stdio_get_by_name(const char *name)
 	return NULL;
 }
 
-struct stdio_dev *stdio_clone(struct stdio_dev *dev)
-{
-	struct stdio_dev *_dev;
-
-	if (!dev)
-		return NULL;
-
-	_dev = calloc(1, sizeof(struct stdio_dev));
-	if (!_dev)
-		return NULL;
-
-	memcpy(_dev, dev, sizeof(struct stdio_dev));
-
-	return _dev;
-}
-
 int stdio_register_dev(struct stdio_dev *dev, struct stdio_dev **devp)
 {
 	struct stdio_dev *_dev;
 
-	_dev = stdio_clone(dev);
+	_dev = memdup(dev, sizeof(*dev));
 	if (!_dev)
 		return -ENODEV;
 	list_add_tail(&_dev->list, &devs.list);
diff --git a/drivers/core/acpi.c b/drivers/core/acpi.c
index 4763963914b..6a431171c8d 100644
--- a/drivers/core/acpi.c
+++ b/drivers/core/acpi.c
@@ -154,10 +154,9 @@ static int add_item(struct acpi_ctx *ctx, struct udevice *dev,
 	if (!item->size)
 		return 0;
 	if (type != TYPE_OTHER) {
-		item->buf = malloc(item->size);
+		item->buf = memdup(start, item->size);
 		if (!item->buf)
 			return log_msg_ret("mem", -ENOMEM);
-		memcpy(item->buf, start, item->size);
 	}
 	item_count++;
 	log_debug("* %s: Added type %d, %p, size %x\n",
diff --git a/drivers/core/ofnode.c b/drivers/core/ofnode.c
index d605c0f7b7c..1388b481031 100644
--- a/drivers/core/ofnode.c
+++ b/drivers/core/ofnode.c
@@ -1798,10 +1798,9 @@ int ofnode_write_prop(ofnode node, const char *propname, const void *value,
 		void *newval;
 
 		if (copy) {
-			newval = malloc(len);
+			newval = memdup(value, len);
 			if (!newval)
 				return log_ret(-ENOMEM);
-			memcpy(newval, value, len);
 			value = newval;
 		}
 		ret = of_write_prop(ofnode_to_np(node), propname, len, value);
diff --git a/drivers/core/root.c b/drivers/core/root.c
index d43645f34dd..1f32f33b295 100644
--- a/drivers/core/root.c
+++ b/drivers/core/root.c
@@ -81,10 +81,9 @@ static int dm_setup_inst(void)
 		/* Now allocate space for the priv/plat data, and copy it in */
 		size = __priv_data_end - __priv_data_start;
 
-		base = calloc(1, size);
+		base = memdup(__priv_data_start, size);
 		if (!base)
 			return log_msg_ret("priv", -ENOMEM);
-		memcpy(base, __priv_data_start, size);
 		gd_set_dm_priv_base(base);
 	}
 
diff --git a/include/linux/string.h b/include/linux/string.h
index a8a6cf4af50..850356d7c3f 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -101,12 +101,12 @@ size_t strcspn(const char *s, const char *reject);
 # define strndup		sandbox_strndup
 #endif
 
-#ifndef __HAVE_ARCH_STRDUP
 extern char * strdup(const char *);
 extern char * strndup(const char *, size_t);
+
 extern const char *strdup_const(const char *s);
 extern void kfree_const(const void *x);
-#endif
+
 #ifndef __HAVE_ARCH_STRSWAB
 extern char * strswab(const char *);
 #endif
@@ -144,7 +144,20 @@ void *memchr_inv(const void *, int, size_t);
  *	memory is available
  *
  */
-char *memdup(const void *src, size_t len);
+void *memdup(const void *src, size_t len);
+
+/**
+ * memdup_nul() - allocate a buffer and copy in the contents, appending a nul byte
+ *
+ * Note that this returns a valid pointer even if @len is 0
+ *
+ * @src: data to copy in
+ * @len: number of bytes to copy
+ * Return: allocated buffer with the copied contents and an extra nul byte,
+ *      or NULL if not enough memory is available
+ *
+ */
+void *memdup_nul(const void *src, size_t len);
 
 unsigned long ustrtoul(const char *cp, char **endp, unsigned int base);
 unsigned long long ustrtoull(const char *cp, char **endp, unsigned int base);
diff --git a/include/stdio_dev.h b/include/stdio_dev.h
index f7f9c10199e..d93604331ff 100644
--- a/include/stdio_dev.h
+++ b/include/stdio_dev.h
@@ -96,7 +96,6 @@ int stdio_add_devices(void);
 int stdio_deregister_dev(struct stdio_dev *dev, int force);
 struct list_head *stdio_get_list(void);
 struct stdio_dev *stdio_get_by_name(const char *name);
-struct stdio_dev *stdio_clone(struct stdio_dev *dev);
 
 int drv_lcd_init(void);
 int drv_video_init(void);
diff --git a/lib/hashtable.c b/lib/hashtable.c
index 75c263b5053..f96a8e686f6 100644
--- a/lib/hashtable.c
+++ b/lib/hashtable.c
@@ -821,13 +821,12 @@ int himport_r(struct hsearch_data *htab,
 	}
 
 	/* we allocate new space to make sure we can write to the array */
-	if ((data = malloc(size + 1)) == NULL) {
-		debug("himport_r: can't malloc %lu bytes\n", (ulong)size + 1);
+	data = memdup_nul(env, size);
+	if (data == NULL) {
+		debug("himport_r: can't duplicate env block\n");
 		__set_errno(ENOMEM);
 		return 0;
 	}
-	memcpy(data, env, size);
-	data[size] = '\0';
 	dp = data;
 
 	/* make a local copy of the list of variables */
diff --git a/lib/string.c b/lib/string.c
index 302efe048b0..37ea8c29561 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -343,41 +343,29 @@ size_t strcspn(const char *s, const char *reject)
 }
 #endif
 
-#ifndef __HAVE_ARCH_STRDUP
+void *memdup_nul(const void *src, size_t len)
+{
+	char *dst;
+
+	if (len + 1 < len)
+		return NULL;
+
+	dst = malloc(len + 1);
+	if (!dst)
+		return NULL;
+
+	dst[len] = '\0';
+	return memcpy(dst, src, len);
+}
+
 char * strdup(const char *s)
 {
-	char *new;
-
-	if ((s == NULL)	||
-	    ((new = malloc (strlen(s) + 1)) == NULL) ) {
-		return NULL;
-	}
-
-	strcpy (new, s);
-	return new;
+	return s ? memdup_nul(s, strlen(s)) : NULL;
 }
 
 char * strndup(const char *s, size_t n)
 {
-	size_t len;
-	char *new;
-
-	if (s == NULL)
-		return NULL;
-
-	len = strlen(s);
-
-	if (n < len)
-		len = n;
-
-	new = malloc(len + 1);
-	if (new == NULL)
-		return NULL;
-
-	strncpy(new, s, len);
-	new[len] = '\0';
-
-	return new;
+	return s ? memdup_nul(s, strnlen(s, n)) : NULL;
 }
 
 /**
@@ -410,7 +398,6 @@ void kfree_const(const void *x)
 		free((void *)x);
 }
 
-#endif
 
 #ifndef __HAVE_ARCH_STRSPN
 /**
@@ -698,17 +685,15 @@ void * memscan(void * addr, int c, size_t size)
 }
 #endif
 
-char *memdup(const void *src, size_t len)
+void *memdup(const void *src, size_t len)
 {
-	char *p;
+	void *p;
 
 	p = malloc(len);
 	if (!p)
 		return NULL;
 
-	memcpy(p, src, len);
-
-	return p;
+	return memcpy(p, src, len);
 }
 
 #ifndef __HAVE_ARCH_STRNSTR
diff --git a/test/lib/string.c b/test/lib/string.c
index f56c2e4c946..db6f28dbfdf 100644
--- a/test/lib/string.c
+++ b/test/lib/string.c
@@ -223,6 +223,40 @@ static int lib_memdup(struct unit_test_state *uts)
 }
 LIB_TEST(lib_memdup, 0);
 
+/** lib_memdup_nul() - unit test for memdup_nul() */
+static int lib_memdup_nul(struct unit_test_state *uts)
+{
+	char buf[BUFLEN];
+	size_t len;
+	char *p, *q;
+
+	/* Zero size should return a buffer containing a single nul byte */
+	p = memdup_nul(NULL, 0);
+	ut_assertnonnull(p);
+	ut_assert(p[0] == '\0');
+	free(p);
+
+	p = memdup_nul(buf, 0);
+	ut_assertnonnull(p);
+	ut_assert(p[0] == '\0');
+	free(p);
+
+	strcpy(buf, TEST_STR);
+	len = sizeof(TEST_STR);
+	p = memdup_nul(buf, len);
+	ut_asserteq_mem(p, buf, len);
+	ut_assert(p[len] == '\0');
+
+	q = memdup_nul(p, len);
+	ut_asserteq_mem(q, buf, len);
+	ut_assert(q[len] == '\0');
+	free(q);
+	free(p);
+
+	return 0;
+}
+LIB_TEST(lib_memdup_nul, 0);
+
 /** lib_strnstr() - unit test for strnstr() */
 static int lib_strnstr(struct unit_test_state *uts)
 {