of: fdt: fix memory initialization for expanded DT

Already existing property flags are filled wrong for properties created from initial FDT. This could cause problems if this DYNAMIC device-tree functions are used later, i.e. properties are attached/detached/replaced. Simply dumping flags from the running system show, that some initial static (not allocated via kzmalloc()) nodes are marked as dynamic.

I putted some debug extensions to property_proc_show(..) :
..

(quoted diff) +4 -0

+       if (OF_IS_DYNAMIC(pp))
+               pr_err("DEBUG: xxx : OF_IS_DYNAMIC\n");
+       if (OF_IS_DETACHED(pp))
+               pr_err("DEBUG: xxx : OF_IS_DETACHED\n");

when you operate on the nodes (e.g.: ~$ cat /proc/device-tree/*some_node*) you will see that those flags are filled wrong, basically in most cases it will dump a DYNAMIC or DETACHED status, which is in not true.
(BTW. this OF_IS_DETACHED is a own define for debug purposes which which just make a test_bit(OF_DETACHED, &x->_flags)

If nodes are dynamic kernel is allowed to kfree() them. But it will crash attempting to do so on the nodes from FDT -- they are not allocated via kzmalloc().

Signed-off-by Wladislav Wiebe <[email protected]>

---
 drivers/of/fdt.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

drivers/of/fdt.c +2 -0

index 6bb7cf2..b10ba00 100644
@@ -392,6 +392,8 @@ static void __unflatten_device_tree(struct boot_param_header *blob,
 	mem = (unsigned long)
 		dt_alloc(size + 4, __alignof__(struct device_node));
 
+	memset((void *)mem, 0, size);
+
 	((__be32 *)mem)[size / 4] = cpu_to_be32(0xdeadbeef);
 
 	pr_debug("  unflattening %lx...\n", mem);

Already existing property flags are filled wrong for properties created from initial FDT. This could cause problems if this DYNAMIC device-tree functions are used later, i.e. properties are attached/detached/replaced. Simply dumping flags from the running system show, that some initial static (not allocated via kzmalloc()) nodes are marked as dynamic.

I putted some debug extensions to property_proc_show(..) :
..

(quoted diff) +4 -0

+       if (OF_IS_DYNAMIC(pp))
+               pr_err("DEBUG: xxx : OF_IS_DYNAMIC\n");
+       if (OF_IS_DETACHED(pp))
+               pr_err("DEBUG: xxx : OF_IS_DETACHED\n");

when you operate on the nodes (e.g.: ~$ cat /proc/device-tree/*some_node*) you will see that those flags are filled wrong, basically in most cases it will dump a DYNAMIC or DETACHED status, which is in not true.
(BTW. this OF_IS_DETACHED is a own define for debug purposes which which just make a test_bit(OF_DETACHED, &x->_flags)

If nodes are dynamic kernel is allowed to kfree() them. But it will crash attempting to do so on the nodes from FDT -- they are not allocated via kzmalloc().

Signed-off-by Wladislav Wiebe <[email protected]>

---
 drivers/of/fdt.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

drivers/of/fdt.c +0 -0

index 6bb7cf2..b10ba00 100644

Quoted 36 lines · Wladislav Wiebe

Already existing property flags are filled wrong for properties created from initial FDT. This could cause problems if this DYNAMIC device-tree functions are used later, i.e. properties are attached/detached/replaced. Simply dumping flags from the running system show, that some initial static (not allocated via kzmalloc()) nodes are marked as dynamic.

I putted some debug extensions to property_proc_show(..) :
..

(quoted diff) +4 -0

+       if (OF_IS_DYNAMIC(pp))
+               pr_err("DEBUG: xxx : OF_IS_DYNAMIC\n");
+       if (OF_IS_DETACHED(pp))
+               pr_err("DEBUG: xxx : OF_IS_DETACHED\n");

when you operate on the nodes (e.g.: ~$ cat /proc/device-tree/*some_node*) you will see that those flags are filled wrong, basically in most cases it will dump a DYNAMIC or DETACHED status, which is in not true.
(BTW. this OF_IS_DETACHED is a own define for debug purposes which which just make a test_bit(OF_DETACHED, &x->_flags)

If nodes are dynamic kernel is allowed to kfree() them. But it will crash attempting to do so on the nodes from FDT -- they are not allocated via kzmalloc().

Signed-off-by Wladislav Wiebe <[email protected]>

---
 drivers/of/fdt.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

drivers/of/fdt.c +0 -0

index 6bb7cf2..b10ba00 100644
@@ -392,6 +392,8 @@ static void __unflatten_device_tree(struct boot_param_header *blob,
      mem = (unsigned long)
              dt_alloc(size + 4, __alignof__(struct device_node));
 

drivers/of/fdt.c static void __unflatten_device_tree(struct boot_param_header *blob, · line 396

Quoted 2 lines

drivers/of/fdt.c +2 -0

+     memset((void *)mem, 0, size);
+

It seems to me that this would be a problem for any call to the early allocation function; early_init_dt_alloc_memory_arch(). There is at least one other call to the allocator via of_alias_scan(). I think this patch is okay for now (I'll add the missing hunk), but it should be revisited.