This will be useful in dynamic node programming when new dt nodes are unflattend
during runtime. Invalid device tree node related errors should be propagated
back to the caller.

Signed-off-by: Vikram Garhwal <vikram.garhwal@amd.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>

---
Changes from v9:
    Replace __be64 with void.
Changes from v7:
    Free allocated memory in case of errors when calling unflatten_dt_node.
---
---
 xen/common/device_tree.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
index 7c6b41c3b4..b6d9f018c6 100644
--- a/xen/common/device_tree.c
+++ b/xen/common/device_tree.c
@@ -2110,6 +2110,9 @@ static int __init __unflatten_device_tree(const void *fdt,
     /* First pass, scan for size */
     start = ((unsigned long)fdt) + fdt_off_dt_struct(fdt);
     size = unflatten_dt_node(fdt, 0, &start, NULL, NULL, 0);
+    if ( !size )
+        return -EINVAL;
+
     size = (size | 3) + 1;
 
     dt_dprintk("  size is %#lx allocating...\n", size);
@@ -2127,11 +2130,21 @@ static int __init __unflatten_device_tree(const void *fdt,
     start = ((unsigned long)fdt) + fdt_off_dt_struct(fdt);
     unflatten_dt_node(fdt, mem, &start, NULL, &allnextp, 0);
     if ( be32_to_cpup((__be32 *)start) != FDT_END )
-        printk(XENLOG_WARNING "Weird tag at end of tree: %08x\n",
+    {
+        printk(XENLOG_ERR "Weird tag at end of tree: %08x\n",
                   *((u32 *)start));
+        xfree((void *)mem);
+        return -EINVAL;
+    }
+
     if ( be32_to_cpu(((__be32 *)mem)[size / 4]) != 0xdeadbeefU )
-        printk(XENLOG_WARNING "End of tree marker overwritten: %08x\n",
+    {
+        printk(XENLOG_ERR "End of tree marker overwritten: %08x\n",
                   be32_to_cpu(((__be32 *)mem)[size / 4]));
+        xfree((void *)mem);
+        return -EINVAL;
+    }
+
     *allnextp = NULL;
 
     dt_dprintk(" <- unflatten_device_tree()\n");
-- 
2.17.1