[PATCH for-4.22 v2] bootfdt: Fix infinite loop in device_tree_for_each_node()

[Dmytro Prokopchuk1 <dmytro_prokopchuk1@xxxxxxxx>]

When a node's depth exceeds DEVICE_TREE_MAX_DEPTH inside the
device_tree_for_each_node() loop, the code prints a warning and
executes 'continue;' statement, which jumps to condition check,
bypassing the iterator update step:

    node = fdt_next_node(fdt, node, &depth).

The node and depth are not updated, the loop repeatedly evaluates
the same too-deep node, causing a hang.

Fix this by wrapping the node processing logic in an 'else' block.
This ensures the loop update step is executed on every iteration,
safely skipping deeply nested nodes and doing the traversal.

Fixes: 40f2ea3df2e2 ("xen/arm: pass node to device_tree_for_each_node")
Signed-off-by: Dmytro Prokopchuk <dmytro_prokopchuk1@xxxxxxxx>
Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
Release-Acked-by: Oleskii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
Changes in v2:
- add R-b from Michal and Oleskii
- add "Fixes:" into commit messsage
- wrap two lines which were over 80 columns
Link to v1:
https://patchew.org/Xen/8836494cb51f6e1f4b094fc690876d344adb47f3.1781955521.git.dmytro._5Fprokopchuk1@xxxxxxxx/
---
 xen/common/device-tree/bootfdt.c | 35 ++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 15 deletions(-)

diff --git a/xen/common/device-tree/bootfdt.c b/xen/common/device-tree/bootfdt.c
index 7c790b9a4d..8e9b45d1a7 100644
--- a/xen/common/device-tree/bootfdt.c
+++ b/xen/common/device-tree/bootfdt.c
@@ -90,23 +90,28 @@ int __init device_tree_for_each_node(const void *fdt, int 
node,
         {
             printk("Warning: device tree node `%s' is nested too deep\n",
                    name);
-            continue;
         }
-
-        as = depth > 0 ? address_cells[depth-1] : 
DT_ROOT_NODE_ADDR_CELLS_DEFAULT;
-        ss = depth > 0 ? size_cells[depth-1] : DT_ROOT_NODE_SIZE_CELLS_DEFAULT;
-
-        address_cells[depth] = device_tree_get_u32(fdt, node,
-                                                   "#address-cells", as);
-        size_cells[depth] = device_tree_get_u32(fdt, node,
-                                                "#size-cells", ss);
-
-        /* skip the first node */
-        if ( node != first_node )
+        else
         {
-            ret = func(fdt, node, name, depth, as, ss, data);
-            if ( ret != 0 )
-                return ret;
+            as = depth > 0 ?
+                 address_cells[depth - 1] :
+                 DT_ROOT_NODE_ADDR_CELLS_DEFAULT;
+            ss = depth > 0 ?
+                 size_cells[depth - 1] :
+                 DT_ROOT_NODE_SIZE_CELLS_DEFAULT;
+
+            address_cells[depth] = device_tree_get_u32(fdt, node,
+                                                       "#address-cells", as);
+            size_cells[depth] = device_tree_get_u32(fdt, node,
+                                                    "#size-cells", ss);
+
+            /* skip the first node */
+            if ( node != first_node )
+            {
+                ret = func(fdt, node, name, depth, as, ss, data);
+                if ( ret != 0 )
+                    return ret;
+            }
         }
 
         node = fdt_next_node(fdt, node, &depth);
-- 
2.43.0