Index: sys/contrib/libfdt/fdt.c
===================================================================
--- sys/contrib/libfdt/fdt.c
+++ sys/contrib/libfdt/fdt.c
@@ -55,7 +55,12 @@
 
 #include "libfdt_internal.h"
 
-int fdt_check_header(const void *fdt)
+/*
+ * Minimal sanity check for a read-only tree. fdt_ro_probe_() checks
+ * that the given buffer contains what appears to be a flattened
+ * device tree with sane information in its header.
+ */
+int fdt_ro_probe_(const void *fdt)
 {
 	if (fdt_magic(fdt) == FDT_MAGIC) {
 		/* Complete tree */
@@ -74,6 +79,78 @@
 	return 0;
 }
 
+static int check_off_(uint32_t hdrsize, uint32_t totalsize, uint32_t off)
+{
+	return (off >= hdrsize) && (off <= totalsize);
+}
+
+static int check_block_(uint32_t hdrsize, uint32_t totalsize,
+			uint32_t base, uint32_t size)
+{
+	if (!check_off_(hdrsize, totalsize, base))
+		return 0; /* block start out of bounds */
+	if ((base + size) < base)
+		return 0; /* overflow */
+	if (!check_off_(hdrsize, totalsize, base + size))
+		return 0; /* block end out of bounds */
+	return 1;
+}
+
+size_t fdt_header_size_(uint32_t version)
+{
+	if (version <= 1)
+		return FDT_V1_SIZE;
+	else if (version <= 2)
+		return FDT_V2_SIZE;
+	else if (version <= 3)
+		return FDT_V3_SIZE;
+	else if (version <= 16)
+		return FDT_V16_SIZE;
+	else
+		return FDT_V17_SIZE;
+}
+
+int fdt_check_header(const void *fdt)
+{
+	size_t hdrsize;
+
+	if (fdt_magic(fdt) != FDT_MAGIC)
+		return -FDT_ERR_BADMAGIC;
+	hdrsize = fdt_header_size(fdt);
+	if ((fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
+	    || (fdt_last_comp_version(fdt) > FDT_LAST_SUPPORTED_VERSION))
+		return -FDT_ERR_BADVERSION;
+	if (fdt_version(fdt) < fdt_last_comp_version(fdt))
+		return -FDT_ERR_BADVERSION;
+
+	if ((fdt_totalsize(fdt) < hdrsize)
+	    || (fdt_totalsize(fdt) > INT_MAX))
+		return -FDT_ERR_TRUNCATED;
+
+	/* Bounds check memrsv block */
+	if (!check_off_(hdrsize, fdt_totalsize(fdt), fdt_off_mem_rsvmap(fdt)))
+		return -FDT_ERR_TRUNCATED;
+
+	/* Bounds check structure block */
+	if (fdt_version(fdt) < 17) {
+		if (!check_off_(hdrsize, fdt_totalsize(fdt),
+				fdt_off_dt_struct(fdt)))
+			return -FDT_ERR_TRUNCATED;
+	} else {
+		if (!check_block_(hdrsize, fdt_totalsize(fdt),
+				  fdt_off_dt_struct(fdt),
+				  fdt_size_dt_struct(fdt)))
+			return -FDT_ERR_TRUNCATED;
+	}
+
+	/* Bounds check strings block */
+	if (!check_block_(hdrsize, fdt_totalsize(fdt),
+			  fdt_off_dt_strings(fdt), fdt_size_dt_strings(fdt)))
+		return -FDT_ERR_TRUNCATED;
+
+	return 0;
+}
+
 const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
 {
 	unsigned absoffset = offset + fdt_off_dt_struct(fdt);
@@ -244,7 +321,7 @@
 
 int fdt_move(const void *fdt, void *buf, int bufsize)
 {
-	FDT_CHECK_HEADER(fdt);
+	FDT_RO_PROBE(fdt);
 
 	if (fdt_totalsize(fdt) > bufsize)
 		return -FDT_ERR_NOSPACE;
Index: sys/contrib/libfdt/fdt_addresses.c
===================================================================
--- sys/contrib/libfdt/fdt_addresses.c
+++ sys/contrib/libfdt/fdt_addresses.c
@@ -1,6 +1,7 @@
 /*
  * libfdt - Flat Device Tree manipulation
  * Copyright (C) 2014 David Gibson <david@gibson.dropbear.id.au>
+ * Copyright (C) 2018 embedded brains GmbH
  *
  * libfdt is dual licensed: you can use it either under the terms of
  * the GPL, or the BSD license, at your option.
@@ -55,42 +56,42 @@
 
 #include "libfdt_internal.h"
 
-int fdt_address_cells(const void *fdt, int nodeoffset)
+static int fdt_cells(const void *fdt, int nodeoffset, const char *name)
 {
-	const fdt32_t *ac;
+	const fdt32_t *c;
 	int val;
 	int len;
 
-	ac = fdt_getprop(fdt, nodeoffset, "#address-cells", &len);
-	if (!ac)
-		return 2;
+	c = fdt_getprop(fdt, nodeoffset, name, &len);
+	if (!c)
+		return len;
 
-	if (len != sizeof(*ac))
+	if (len != sizeof(*c))
 		return -FDT_ERR_BADNCELLS;
 
-	val = fdt32_to_cpu(*ac);
+	val = fdt32_to_cpu(*c);
 	if ((val <= 0) || (val > FDT_MAX_NCELLS))
 		return -FDT_ERR_BADNCELLS;
 
 	return val;
 }
 
-int fdt_size_cells(const void *fdt, int nodeoffset)
+int fdt_address_cells(const void *fdt, int nodeoffset)
 {
-	const fdt32_t *sc;
 	int val;
-	int len;
 
-	sc = fdt_getprop(fdt, nodeoffset, "#size-cells", &len);
-	if (!sc)
+	val = fdt_cells(fdt, nodeoffset, "#address-cells");
+	if (val == -FDT_ERR_NOTFOUND)
 		return 2;
+	return val;
+}
 
-	if (len != sizeof(*sc))
-		return -FDT_ERR_BADNCELLS;
+int fdt_size_cells(const void *fdt, int nodeoffset)
+{
+	int val;
 
-	val = fdt32_to_cpu(*sc);
-	if ((val < 0) || (val > FDT_MAX_NCELLS))
-		return -FDT_ERR_BADNCELLS;
-
+	val = fdt_cells(fdt, nodeoffset, "#size-cells");
+	if (val == -FDT_ERR_NOTFOUND)
+		return 1;
 	return val;
 }
Index: sys/contrib/libfdt/fdt_overlay.c
===================================================================
--- sys/contrib/libfdt/fdt_overlay.c
+++ sys/contrib/libfdt/fdt_overlay.c
@@ -697,7 +697,7 @@
 	int len = 0, namelen;
 	const char *name;
 
-	FDT_CHECK_HEADER(fdt);
+	FDT_RO_PROBE(fdt);
 
 	for (;;) {
 		name = fdt_get_name(fdt, nodeoffset, &namelen);
@@ -866,8 +866,8 @@
 	uint32_t delta = fdt_get_max_phandle(fdt);
 	int ret;
 
-	FDT_CHECK_HEADER(fdt);
-	FDT_CHECK_HEADER(fdto);
+	FDT_RO_PROBE(fdt);
+	FDT_RO_PROBE(fdto);
 
 	ret = overlay_adjust_local_phandles(fdto, delta);
 	if (ret)
Index: sys/contrib/libfdt/fdt_ro.c
===================================================================
--- sys/contrib/libfdt/fdt_ro.c
+++ sys/contrib/libfdt/fdt_ro.c
@@ -76,17 +76,72 @@
 		return 0;
 }
 
+const char *fdt_get_string(const void *fdt, int stroffset, int *lenp)
+{
+	uint32_t absoffset = stroffset + fdt_off_dt_strings(fdt);
+	size_t len;
+	int err;
+	const char *s, *n;
+
+	err = fdt_ro_probe_(fdt);
+	if (err != 0)
+		goto fail;
+
+	err = -FDT_ERR_BADOFFSET;
+	if (absoffset >= fdt_totalsize(fdt))
+		goto fail;
+	len = fdt_totalsize(fdt) - absoffset;
+
+	if (fdt_magic(fdt) == FDT_MAGIC) {
+		if (stroffset < 0)
+			goto fail;
+		if (fdt_version(fdt) >= 17) {
+			if (stroffset >= fdt_size_dt_strings(fdt))
+				goto fail;
+			if ((fdt_size_dt_strings(fdt) - stroffset) < len)
+				len = fdt_size_dt_strings(fdt) - stroffset;
+		}
+	} else if (fdt_magic(fdt) == FDT_SW_MAGIC) {
+		if ((stroffset >= 0)
+		    || (stroffset < -fdt_size_dt_strings(fdt)))
+			goto fail;
+		if ((-stroffset) < len)
+			len = -stroffset;
+	} else {
+		err = -FDT_ERR_INTERNAL;
+		goto fail;
+	}
+
+	s = (const char *)fdt + absoffset;
+	n = memchr(s, '\0', len);
+	if (!n) {
+		/* missing terminating NULL */
+		err = -FDT_ERR_TRUNCATED;
+		goto fail;
+	}
+
+	if (lenp)
+		*lenp = n - s;
+	return s;
+
+fail:
+	if (lenp)
+		*lenp = err;
+	return NULL;
+}
+
 const char *fdt_string(const void *fdt, int stroffset)
 {
-	return (const char *)fdt + fdt_off_dt_strings(fdt) + stroffset;
+	return fdt_get_string(fdt, stroffset, NULL);
 }
 
 static int fdt_string_eq_(const void *fdt, int stroffset,
 			  const char *s, int len)
 {
-	const char *p = fdt_string(fdt, stroffset);
+	int slen;
+	const char *p = fdt_get_string(fdt, stroffset, &slen);
 
-	return (strlen(p) == len) && (memcmp(p, s, len) == 0);
+	return p && (slen == len) && (memcmp(p, s, len) == 0);
 }
 
 uint32_t fdt_get_max_phandle(const void *fdt)
@@ -115,21 +170,42 @@
 	return 0;
 }
 
+static const struct fdt_reserve_entry *fdt_mem_rsv(const void *fdt, int n)
+{
+	int offset = n * sizeof(struct fdt_reserve_entry);
+	int absoffset = fdt_off_mem_rsvmap(fdt) + offset;
+
+	if (absoffset < fdt_off_mem_rsvmap(fdt))
+		return NULL;
+	if (absoffset > fdt_totalsize(fdt) - sizeof(struct fdt_reserve_entry))
+		return NULL;
+	return fdt_mem_rsv_(fdt, n);
+}
+
 int fdt_get_mem_rsv(const void *fdt, int n, uint64_t *address, uint64_t *size)
 {
-	FDT_CHECK_HEADER(fdt);
-	*address = fdt64_to_cpu(fdt_mem_rsv_(fdt, n)->address);
-	*size = fdt64_to_cpu(fdt_mem_rsv_(fdt, n)->size);
+	const struct fdt_reserve_entry *re;
+
+	FDT_RO_PROBE(fdt);
+	re = fdt_mem_rsv(fdt, n);
+	if (!re)
+		return -FDT_ERR_BADOFFSET;
+
+	*address = fdt64_ld(&re->address);
+	*size = fdt64_ld(&re->size);
 	return 0;
 }
 
 int fdt_num_mem_rsv(const void *fdt)
 {
-	int i = 0;
+	int i;
+	const struct fdt_reserve_entry *re;
 
-	while (fdt64_to_cpu(fdt_mem_rsv_(fdt, i)->size) != 0)
-		i++;
-	return i;
+	for (i = 0; (re = fdt_mem_rsv(fdt, i)) != NULL; i++) {
+		if (fdt64_ld(&re->size) == 0)
+			return i;
+	}
+	return -FDT_ERR_TRUNCATED;
 }
 
 static int nextprop_(const void *fdt, int offset)
@@ -161,7 +237,7 @@
 {
 	int depth;
 
-	FDT_CHECK_HEADER(fdt);
+	FDT_RO_PROBE(fdt);
 
 	for (depth = 0;
 	     (offset >= 0) && (depth >= 0);
@@ -187,7 +263,7 @@
 	const char *p = path;
 	int offset = 0;
 
-	FDT_CHECK_HEADER(fdt);
+	FDT_RO_PROBE(fdt);
 
 	/* see if we have an alias */
 	if (*path != '/') {
@@ -237,7 +313,7 @@
 	const char *nameptr;
 	int err;
 
-	if (((err = fdt_check_header(fdt)) != 0)
+	if (((err = fdt_ro_probe_(fdt)) != 0)
 	    || ((err = fdt_check_node_offset_(fdt, nodeoffset)) < 0))
 			goto fail;
 
@@ -303,7 +379,7 @@
 	prop = fdt_offset_ptr_(fdt, offset);
 
 	if (lenp)
-		*lenp = fdt32_to_cpu(prop->len);
+		*lenp = fdt32_ld(&prop->len);
 
 	return prop;
 }
@@ -340,7 +416,7 @@
 			offset = -FDT_ERR_INTERNAL;
 			break;
 		}
-		if (fdt_string_eq_(fdt, fdt32_to_cpu(prop->nameoff),
+		if (fdt_string_eq_(fdt, fdt32_ld(&prop->nameoff),
 				   name, namelen)) {
 			if (poffset)
 				*poffset = offset;
@@ -393,7 +469,7 @@
 
 	/* Handle realignment */
 	if (fdt_version(fdt) < 0x10 && (poffset + sizeof(*prop)) % 8 &&
-	    fdt32_to_cpu(prop->len) >= 8)
+	    fdt32_ld(&prop->len) >= 8)
 		return prop->data + 4;
 	return prop->data;
 }
@@ -406,12 +482,22 @@
 	prop = fdt_get_property_by_offset_(fdt, offset, lenp);
 	if (!prop)
 		return NULL;
-	if (namep)
-		*namep = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
+	if (namep) {
+		const char *name;
+		int namelen;
+		name = fdt_get_string(fdt, fdt32_ld(&prop->nameoff),
+				      &namelen);
+		if (!name) {
+			if (lenp)
+				*lenp = namelen;
+			return NULL;
+		}
+		*namep = name;
+	}
 
 	/* Handle realignment */
 	if (fdt_version(fdt) < 0x10 && (offset + sizeof(*prop)) % 8 &&
-	    fdt32_to_cpu(prop->len) >= 8)
+	    fdt32_ld(&prop->len) >= 8)
 		return prop->data + 4;
 	return prop->data;
 }
@@ -436,7 +522,7 @@
 			return 0;
 	}
 
-	return fdt32_to_cpu(*php);
+	return fdt32_ld(php);
 }
 
 const char *fdt_get_alias_namelen(const void *fdt,
@@ -462,7 +548,7 @@
 	int offset, depth, namelen;
 	const char *name;
 
-	FDT_CHECK_HEADER(fdt);
+	FDT_RO_PROBE(fdt);
 
 	if (buflen < 2)
 		return -FDT_ERR_NOSPACE;
@@ -514,7 +600,7 @@
 	int offset, depth;
 	int supernodeoffset = -FDT_ERR_INTERNAL;
 
-	FDT_CHECK_HEADER(fdt);
+	FDT_RO_PROBE(fdt);
 
 	if (supernodedepth < 0)
 		return -FDT_ERR_NOTFOUND;
@@ -573,7 +659,7 @@
 	const void *val;
 	int len;
 
-	FDT_CHECK_HEADER(fdt);
+	FDT_RO_PROBE(fdt);
 
 	/* FIXME: The algorithm here is pretty horrible: we scan each
 	 * property of a node in fdt_getprop(), then if that didn't
@@ -599,7 +685,7 @@
 	if ((phandle == 0) || (phandle == -1))
 		return -FDT_ERR_BADPHANDLE;
 
-	FDT_CHECK_HEADER(fdt);
+	FDT_RO_PROBE(fdt);
 
 	/* FIXME: The algorithm here is pretty horrible: we
 	 * potentially scan each property of a node in
@@ -752,7 +838,7 @@
 {
 	int offset, err;
 
-	FDT_CHECK_HEADER(fdt);
+	FDT_RO_PROBE(fdt);
 
 	/* FIXME: The algorithm here is pretty horrible: we scan each
 	 * property of a node in fdt_node_check_compatible(), then if
@@ -770,4 +856,67 @@
 	}
 
 	return offset; /* error from fdt_next_node() */
+}
+
+int fdt_check_full(const void *fdt, size_t bufsize)
+{
+	int err;
+	int num_memrsv;
+	int offset, nextoffset = 0;
+	uint32_t tag;
+	unsigned depth = 0;
+	const void *prop;
+	const char *propname;
+
+	if (bufsize < FDT_V1_SIZE)
+		return -FDT_ERR_TRUNCATED;
+	err = fdt_check_header(fdt);
+	if (err != 0)
+		return err;
+	if (bufsize < fdt_totalsize(fdt))
+		return -FDT_ERR_TRUNCATED;
+
+	num_memrsv = fdt_num_mem_rsv(fdt);
+	if (num_memrsv < 0)
+		return num_memrsv;
+
+	while (1) {
+		offset = nextoffset;
+		tag = fdt_next_tag(fdt, offset, &nextoffset);
+
+		if (nextoffset < 0)
+			return nextoffset;
+
+		switch (tag) {
+		case FDT_NOP:
+			break;
+
+		case FDT_END:
+			if (depth != 0)
+				return -FDT_ERR_BADSTRUCTURE;
+			return 0;
+
+		case FDT_BEGIN_NODE:
+			depth++;
+			if (depth > INT_MAX)
+				return -FDT_ERR_BADSTRUCTURE;
+			break;
+
+		case FDT_END_NODE:
+			if (depth == 0)
+				return -FDT_ERR_BADSTRUCTURE;
+			depth--;
+			break;
+
+		case FDT_PROP:
+			prop = fdt_getprop_by_offset(fdt, offset, &propname,
+						     &err);
+			if (!prop)
+				return err;
+			break;
+
+		default:
+			return -FDT_ERR_INTERNAL;
+		}
+	}
 }
Index: sys/contrib/libfdt/fdt_rw.c
===================================================================
--- sys/contrib/libfdt/fdt_rw.c
+++ sys/contrib/libfdt/fdt_rw.c
@@ -67,9 +67,9 @@
 		    (fdt_off_dt_strings(fdt) + fdt_size_dt_strings(fdt)));
 }
 
-static int fdt_rw_check_header_(void *fdt)
+static int fdt_rw_probe_(void *fdt)
 {
-	FDT_CHECK_HEADER(fdt);
+	FDT_RO_PROBE(fdt);
 
 	if (fdt_version(fdt) < 17)
 		return -FDT_ERR_BADVERSION;
@@ -82,10 +82,10 @@
 	return 0;
 }
 
-#define FDT_RW_CHECK_HEADER(fdt) \
+#define FDT_RW_PROBE(fdt) \
 	{ \
 		int err_; \
-		if ((err_ = fdt_rw_check_header_(fdt)) != 0) \
+		if ((err_ = fdt_rw_probe_(fdt)) != 0) \
 			return err_; \
 	}
 
@@ -176,7 +176,7 @@
 	struct fdt_reserve_entry *re;
 	int err;
 
-	FDT_RW_CHECK_HEADER(fdt);
+	FDT_RW_PROBE(fdt);
 
 	re = fdt_mem_rsv_w_(fdt, fdt_num_mem_rsv(fdt));
 	err = fdt_splice_mem_rsv_(fdt, re, 0, 1);
@@ -192,7 +192,7 @@
 {
 	struct fdt_reserve_entry *re = fdt_mem_rsv_w_(fdt, n);
 
-	FDT_RW_CHECK_HEADER(fdt);
+	FDT_RW_PROBE(fdt);
 
 	if (n >= fdt_num_mem_rsv(fdt))
 		return -FDT_ERR_NOTFOUND;
@@ -252,7 +252,7 @@
 	int oldlen, newlen;
 	int err;
 
-	FDT_RW_CHECK_HEADER(fdt);
+	FDT_RW_PROBE(fdt);
 
 	namep = (char *)(uintptr_t)fdt_get_name(fdt, nodeoffset, &oldlen);
 	if (!namep)
@@ -275,7 +275,7 @@
 	struct fdt_property *prop;
 	int err;
 
-	FDT_RW_CHECK_HEADER(fdt);
+	FDT_RW_PROBE(fdt);
 
 	err = fdt_resize_property_(fdt, nodeoffset, name, len, &prop);
 	if (err == -FDT_ERR_NOTFOUND)
@@ -308,7 +308,7 @@
 	struct fdt_property *prop;
 	int err, oldlen, newlen;
 
-	FDT_RW_CHECK_HEADER(fdt);
+	FDT_RW_PROBE(fdt);
 
 	prop = fdt_get_property_w(fdt, nodeoffset, name, &oldlen);
 	if (prop) {
@@ -334,7 +334,7 @@
 	struct fdt_property *prop;
 	int len, proplen;
 
-	FDT_RW_CHECK_HEADER(fdt);
+	FDT_RW_PROBE(fdt);
 
 	prop = fdt_get_property_w(fdt, nodeoffset, name, &len);
 	if (!prop)
@@ -354,7 +354,7 @@
 	uint32_t tag;
 	fdt32_t *endtag;
 
-	FDT_RW_CHECK_HEADER(fdt);
+	FDT_RW_PROBE(fdt);
 
 	offset = fdt_subnode_offset_namelen(fdt, parentoffset, name, namelen);
 	if (offset >= 0)
@@ -394,7 +394,7 @@
 {
 	int endoffset;
 
-	FDT_RW_CHECK_HEADER(fdt);
+	FDT_RW_PROBE(fdt);
 
 	endoffset = fdt_node_end_offset_(fdt, nodeoffset);
 	if (endoffset < 0)
@@ -435,7 +435,7 @@
 	const char *fdtend = fdtstart + fdt_totalsize(fdt);
 	char *tmp;
 
-	FDT_CHECK_HEADER(fdt);
+	FDT_RO_PROBE(fdt);
 
 	mem_rsv_size = (fdt_num_mem_rsv(fdt)+1)
 		* sizeof(struct fdt_reserve_entry);
@@ -494,7 +494,7 @@
 {
 	int mem_rsv_size;
 
-	FDT_RW_CHECK_HEADER(fdt);
+	FDT_RW_PROBE(fdt);
 
 	mem_rsv_size = (fdt_num_mem_rsv(fdt)+1)
 		* sizeof(struct fdt_reserve_entry);
Index: sys/contrib/libfdt/fdt_sw.c
===================================================================
--- sys/contrib/libfdt/fdt_sw.c
+++ sys/contrib/libfdt/fdt_sw.c
@@ -55,21 +55,77 @@
 
 #include "libfdt_internal.h"
 
-static int fdt_sw_check_header_(void *fdt)
+static int fdt_sw_probe_(void *fdt)
 {
-	if (fdt_magic(fdt) != FDT_SW_MAGIC)
+	if (fdt_magic(fdt) == FDT_MAGIC)
+		return -FDT_ERR_BADSTATE;
+	else if (fdt_magic(fdt) != FDT_SW_MAGIC)
 		return -FDT_ERR_BADMAGIC;
-	/* FIXME: should check more details about the header state */
 	return 0;
 }
 
-#define FDT_SW_CHECK_HEADER(fdt) \
+#define FDT_SW_PROBE(fdt) \
 	{ \
 		int err; \
-		if ((err = fdt_sw_check_header_(fdt)) != 0) \
+		if ((err = fdt_sw_probe_(fdt)) != 0) \
 			return err; \
 	}
 
+/* 'memrsv' state:	Initial state after fdt_create()
+ *
+ * Allowed functions:
+ *	fdt_add_reservmap_entry()
+ *	fdt_finish_reservemap()		[moves to 'struct' state]
+ */
+static int fdt_sw_probe_memrsv_(void *fdt)
+{
+	int err = fdt_sw_probe_(fdt);
+	if (err)
+		return err;
+
+	if (fdt_off_dt_strings(fdt) != 0)
+		return -FDT_ERR_BADSTATE;
+	return 0;
+}
+
+#define FDT_SW_PROBE_MEMRSV(fdt) \
+	{ \
+		int err; \
+		if ((err = fdt_sw_probe_memrsv_(fdt)) != 0) \
+			return err; \
+	}
+
+/* 'struct' state:	Enter this state after fdt_finish_reservemap()
+ *
+ * Allowed functions:
+ *	fdt_begin_node()
+ *	fdt_end_node()
+ *	fdt_property*()
+ *	fdt_finish()			[moves to 'complete' state]
+ */
+static int fdt_sw_probe_struct_(void *fdt)
+{
+	int err = fdt_sw_probe_(fdt);
+	if (err)
+		return err;
+
+	if (fdt_off_dt_strings(fdt) != fdt_totalsize(fdt))
+		return -FDT_ERR_BADSTATE;
+	return 0;
+}
+
+#define FDT_SW_PROBE_STRUCT(fdt) \
+	{ \
+		int err; \
+		if ((err = fdt_sw_probe_struct_(fdt)) != 0) \
+			return err; \
+	}
+
+/* 'complete' state:	Enter this state after fdt_finish()
+ *
+ * Allowed functions: none
+ */
+
 static void *fdt_grab_space_(void *fdt, size_t len)
 {
 	int offset = fdt_size_dt_struct(fdt);
@@ -87,9 +143,11 @@
 
 int fdt_create(void *buf, int bufsize)
 {
+	const size_t hdrsize = FDT_ALIGN(sizeof(struct fdt_header),
+					 sizeof(struct fdt_reserve_entry));
 	void *fdt = buf;
 
-	if (bufsize < sizeof(struct fdt_header))
+	if (bufsize < hdrsize)
 		return -FDT_ERR_NOSPACE;
 
 	memset(buf, 0, bufsize);
@@ -99,10 +157,9 @@
 	fdt_set_last_comp_version(fdt, FDT_FIRST_SUPPORTED_VERSION);
 	fdt_set_totalsize(fdt,  bufsize);
 
-	fdt_set_off_mem_rsvmap(fdt, FDT_ALIGN(sizeof(struct fdt_header),
-					      sizeof(struct fdt_reserve_entry)));
+	fdt_set_off_mem_rsvmap(fdt, hdrsize);
 	fdt_set_off_dt_struct(fdt, fdt_off_mem_rsvmap(fdt));
-	fdt_set_off_dt_strings(fdt, bufsize);
+	fdt_set_off_dt_strings(fdt, 0);
 
 	return 0;
 }
@@ -112,11 +169,14 @@
 	size_t headsize, tailsize;
 	char *oldtail, *newtail;
 
-	FDT_SW_CHECK_HEADER(fdt);
+	FDT_SW_PROBE(fdt);
 
-	headsize = fdt_off_dt_struct(fdt);
+	headsize = fdt_off_dt_struct(fdt) + fdt_size_dt_struct(fdt);
 	tailsize = fdt_size_dt_strings(fdt);
 
+	if ((headsize + tailsize) > fdt_totalsize(fdt))
+		return -FDT_ERR_INTERNAL;
+
 	if ((headsize + tailsize) > bufsize)
 		return -FDT_ERR_NOSPACE;
 
@@ -133,8 +193,9 @@
 		memmove(buf, fdt, headsize);
 	}
 
-	fdt_set_off_dt_strings(buf, bufsize);
 	fdt_set_totalsize(buf, bufsize);
+	if (fdt_off_dt_strings(buf))
+		fdt_set_off_dt_strings(buf, bufsize);
 
 	return 0;
 }
@@ -144,11 +205,8 @@
 	struct fdt_reserve_entry *re;
 	int offset;
 
-	FDT_SW_CHECK_HEADER(fdt);
+	FDT_SW_PROBE_MEMRSV(fdt);
 
-	if (fdt_size_dt_struct(fdt))
-		return -FDT_ERR_BADSTATE;
-
 	offset = fdt_off_dt_struct(fdt);
 	if ((offset + sizeof(*re)) > fdt_totalsize(fdt))
 		return -FDT_ERR_NOSPACE;
@@ -164,16 +222,23 @@
 
 int fdt_finish_reservemap(void *fdt)
 {
-	return fdt_add_reservemap_entry(fdt, 0, 0);
+	int err = fdt_add_reservemap_entry(fdt, 0, 0);
+
+	if (err)
+		return err;
+
+	fdt_set_off_dt_strings(fdt, fdt_totalsize(fdt));
+	return 0;
 }
 
 int fdt_begin_node(void *fdt, const char *name)
 {
 	struct fdt_node_header *nh;
-	int namelen = strlen(name) + 1;
+	int namelen;
 
-	FDT_SW_CHECK_HEADER(fdt);
+	FDT_SW_PROBE_STRUCT(fdt);
 
+	namelen = strlen(name) + 1;
 	nh = fdt_grab_space_(fdt, sizeof(*nh) + FDT_TAGALIGN(namelen));
 	if (! nh)
 		return -FDT_ERR_NOSPACE;
@@ -187,7 +252,7 @@
 {
 	fdt32_t *en;
 
-	FDT_SW_CHECK_HEADER(fdt);
+	FDT_SW_PROBE_STRUCT(fdt);
 
 	en = fdt_grab_space_(fdt, FDT_TAGSIZE);
 	if (! en)
@@ -225,7 +290,7 @@
 	struct fdt_property *prop;
 	int nameoff;
 
-	FDT_SW_CHECK_HEADER(fdt);
+	FDT_SW_PROBE_STRUCT(fdt);
 
 	nameoff = fdt_find_add_string_(fdt, name);
 	if (nameoff == 0)
@@ -262,7 +327,7 @@
 	uint32_t tag;
 	int offset, nextoffset;
 
-	FDT_SW_CHECK_HEADER(fdt);
+	FDT_SW_PROBE_STRUCT(fdt);
 
 	/* Add terminator */
 	end = fdt_grab_space_(fdt, sizeof(*end));
Index: sys/contrib/libfdt/libfdt.h
===================================================================
--- sys/contrib/libfdt/libfdt.h
+++ sys/contrib/libfdt/libfdt.h
@@ -90,8 +90,9 @@
 
 /* Error codes: codes for bad device tree blobs */
 #define FDT_ERR_TRUNCATED	8
-	/* FDT_ERR_TRUNCATED: Structure block of the given device tree
-	 * ends without an FDT_END tag. */
+	/* FDT_ERR_TRUNCATED: FDT or a sub-block is improperly
+	 * terminated (overflows, goes outside allowed bounds, or
+	 * isn't properly terminated).  */
 #define FDT_ERR_BADMAGIC	9
 	/* FDT_ERR_BADMAGIC: Given "device tree" appears not to be a
 	 * device tree at all - it is missing the flattened device
@@ -153,6 +154,37 @@
 
 uint32_t fdt_next_tag(const void *fdt, int offset, int *nextoffset);
 
+/*
+ * Alignment helpers:
+ *     These helpers access words from a device tree blob.  They're
+ *     built to work even with unaligned pointers on platforms (ike
+ *     ARM) that don't like unaligned loads and stores
+ */
+
+static inline uint32_t fdt32_ld(const fdt32_t *p)
+{
+	const uint8_t *bp = (const uint8_t *)p;
+
+	return ((uint32_t)bp[0] << 24)
+		| ((uint32_t)bp[1] << 16)
+		| ((uint32_t)bp[2] << 8)
+		| bp[3];
+}
+
+static inline uint64_t fdt64_ld(const fdt64_t *p)
+{
+	const uint8_t *bp = (const uint8_t *)p;
+
+	return ((uint64_t)bp[0] << 56)
+		| ((uint64_t)bp[1] << 48)
+		| ((uint64_t)bp[2] << 40)
+		| ((uint64_t)bp[3] << 32)
+		| ((uint64_t)bp[4] << 24)
+		| ((uint64_t)bp[5] << 16)
+		| ((uint64_t)bp[6] << 8)
+		| bp[7];
+}
+
 /**********************************************************************/
 /* Traversal functions                                                */
 /**********************************************************************/
@@ -195,7 +227,7 @@
  *		...
  *	}
  *
- *	if ((node < 0) && (node != -FDT_ERR_NOT_FOUND)) {
+ *	if ((node < 0) && (node != -FDT_ERR_NOTFOUND)) {
  *		Error handling
  *	}
  *
@@ -213,7 +245,7 @@
 /* General functions                                                  */
 /**********************************************************************/
 #define fdt_get_header(fdt, field) \
-	(fdt32_to_cpu(((const struct fdt_header *)(fdt))->field))
+	(fdt32_ld(&((const struct fdt_header *)(fdt))->field))
 #define fdt_magic(fdt)			(fdt_get_header(fdt, magic))
 #define fdt_totalsize(fdt)		(fdt_get_header(fdt, totalsize))
 #define fdt_off_dt_struct(fdt)		(fdt_get_header(fdt, off_dt_struct))
@@ -244,18 +276,31 @@
 #undef fdt_set_hdr_
 
 /**
- * fdt_check_header - sanity check a device tree or possible device tree
+ * fdt_header_size - return the size of the tree's header
+ * @fdt: pointer to a flattened device tree
+ */
+size_t fdt_header_size_(uint32_t version);
+static inline size_t fdt_header_size(const void *fdt)
+{
+	return fdt_header_size_(fdt_version(fdt));
+}
+
+/**
+ * fdt_check_header - sanity check a device tree header
+
  * @fdt: pointer to data which might be a flattened device tree
  *
  * fdt_check_header() checks that the given buffer contains what
- * appears to be a flattened device tree with sane information in its
- * header.
+ * appears to be a flattened device tree, and that the header contains
+ * valid information (to the extent that can be determined from the
+ * header alone).
  *
  * returns:
  *     0, if the buffer appears to contain a valid device tree
  *     -FDT_ERR_BADMAGIC,
  *     -FDT_ERR_BADVERSION,
- *     -FDT_ERR_BADSTATE, standard meanings, as above
+ *     -FDT_ERR_BADSTATE,
+ *     -FDT_ERR_TRUNCATED, standard meanings, as above
  */
 int fdt_check_header(const void *fdt);
 
@@ -284,7 +329,25 @@
 /* Read-only functions                                                */
 /**********************************************************************/
 
+int fdt_check_full(const void *fdt, size_t bufsize);
+
 /**
+ * fdt_get_string - retrieve a string from the strings block of a device tree
+ * @fdt: pointer to the device tree blob
+ * @stroffset: offset of the string within the strings block (native endian)
+ * @lenp: optional pointer to return the string's length
+ *
+ * fdt_get_string() retrieves a pointer to a single string from the
+ * strings block of the device tree blob at fdt, and optionally also
+ * returns the string's length in *lenp.
+ *
+ * returns:
+ *     a pointer to the string, on success
+ *     NULL, if stroffset is out of bounds, or doesn't point to a valid string
+ */
+const char *fdt_get_string(const void *fdt, int stroffset, int *lenp);
+
+/**
  * fdt_string - retrieve a string from the strings block of a device tree
  * @fdt: pointer to the device tree blob
  * @stroffset: offset of the string within the strings block (native endian)
@@ -294,7 +357,7 @@
  *
  * returns:
  *     a pointer to the string, on success
- *     NULL, if stroffset is out of bounds
+ *     NULL, if stroffset is out of bounds, or doesn't point to a valid string
  */
 const char *fdt_string(const void *fdt, int stroffset);
 
@@ -503,7 +566,7 @@
  *		...
  *	}
  *
- *	if ((property < 0) && (property != -FDT_ERR_NOT_FOUND)) {
+ *	if ((property < 0) && (property != -FDT_ERR_NOTFOUND)) {
  *		Error handling
  *	}
  *
@@ -606,7 +669,7 @@
 /**
  * fdt_getprop_by_offset - retrieve the value of a property at a given offset
  * @fdt: pointer to the device tree blob
- * @ffset: offset of the property to read
+ * @offset: offset of the property to read
  * @namep: pointer to a string variable (will be overwritten) or NULL
  * @lenp: pointer to an integer variable (will be overwritten) or NULL
  *
@@ -1090,7 +1153,7 @@
  *
  * returns:
  *	0 <= n < FDT_MAX_NCELLS, on success
- *      2, if the node has no #address-cells property
+ *      1, if the node has no #size-cells property
  *      -FDT_ERR_BADNCELLS, if the node has a badly formatted or invalid
  *		#size-cells property
  *	-FDT_ERR_BADMAGIC,
@@ -1313,10 +1376,13 @@
 	fdt64_t tmp = cpu_to_fdt64(val);
 	return fdt_property(fdt, name, &tmp, sizeof(tmp));
 }
+
+#ifndef SWIG /* Not available in Python */
 static inline int fdt_property_cell(void *fdt, const char *name, uint32_t val)
 {
 	return fdt_property_u32(fdt, name, val);
 }
+#endif
 
 /**
  * fdt_property_placeholder - add a new property and return a ptr to its value
Index: sys/contrib/libfdt/libfdt_env.h
===================================================================
--- sys/contrib/libfdt/libfdt_env.h
+++ sys/contrib/libfdt/libfdt_env.h
@@ -58,11 +58,13 @@
 #include <sys/types.h>
 #include <sys/systm.h>
 #include <sys/stdint.h>
+#include <sys/limits.h>
 #else
 #include <stddef.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
+#include <limits.h>
 #endif
 
 #ifdef __CHECKER__
Index: sys/contrib/libfdt/libfdt_internal.h
===================================================================
--- sys/contrib/libfdt/libfdt_internal.h
+++ sys/contrib/libfdt/libfdt_internal.h
@@ -55,10 +55,11 @@
 #define FDT_ALIGN(x, a)		(((x) + (a) - 1) & ~((a) - 1))
 #define FDT_TAGALIGN(x)		(FDT_ALIGN((x), FDT_TAGSIZE))
 
-#define FDT_CHECK_HEADER(fdt) \
+int fdt_ro_probe_(const void *fdt);
+#define FDT_RO_PROBE(fdt)			\
 	{ \
 		int err_; \
-		if ((err_ = fdt_check_header(fdt)) != 0) \
+		if ((err_ = fdt_ro_probe_(fdt)) != 0)	\
 			return err_; \
 	}