From: Frank Rowand <frank.rowand@xxxxxxxx>
The Devicetree standard specifies an 8 byte alignment of the FDT.
Code in libfdt expects this alignment for an FDT image in memory.
kmemdup() returns 4 byte alignment on openrisc. Replace kmemdup()
with kmalloc(), align pointer, memcpy() to get proper alignment.
The 4 byte alignment exposed a related bug which triggered a crash
on openrisc with:
commit 79edff12060f ("scripts/dtc: Update to upstream version v1.6.0-51-g183df9e9c2b9")
as reported in:
https://lore.kernel.org/lkml/20210327224116.69309-1-linux@xxxxxxxxxxxx/
Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Frank Rowand <frank.rowand@xxxxxxxx>
---
drivers/of/of_private.h | 2 ++
drivers/of/overlay.c | 8 ++++++--
drivers/of/unittest.c | 9 +++++++--
3 files changed, 15 insertions(+), 4 deletions(-)
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index d9e6a324de0a..d717efbd637d 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -8,6 +8,8 @@
* Copyright (C) 1996-2005 Paul Mackerras.
*/
+#define FDT_ALIGN_SIZE 8
+
/**
* struct alias_prop - Alias property in 'aliases' node
* @link: List node to link the structure in aliases_lookup list
diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 50bbe0edf538..8b40711ed202 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -1014,7 +1014,7 @@ static int of_overlay_apply(const void *fdt, struct device_node *tree,
int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size,
int *ovcs_id)
{
- const void *new_fdt;
+ void *new_fdt;
int ret;
u32 size;
struct device_node *overlay_root;
@@ -1036,10 +1036,14 @@ int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size,
* Must create permanent copy of FDT because of_fdt_unflatten_tree()
* will create pointers to the passed in FDT in the unflattened tree.
*/
- new_fdt = kmemdup(overlay_fdt, size, GFP_KERNEL);
+ size += FDT_ALIGN_SIZE;
+ new_fdt = kmalloc(size, GFP_KERNEL);
if (!new_fdt)
return -ENOMEM;
+ new_fdt = PTR_ALIGN(new_fdt, FDT_ALIGN_SIZE);
+ memcpy(new_fdt, overlay_fdt, size);
+
of_fdt_unflatten_tree(new_fdt, NULL, &overlay_root);
if (!overlay_root) {
pr_err("unable to unflatten overlay_fdt\n");
diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index eb100627c186..edd6ce807691 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -22,6 +22,7 @@
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/platform_device.h>
+#include <linux/kernel.h>
#include <linux/i2c.h>
#include <linux/i2c-mux.h>
@@ -1415,7 +1416,7 @@ static int __init unittest_data_add(void)
*/
extern uint8_t __dtb_testcases_begin[];
extern uint8_t __dtb_testcases_end[];
- const int size = __dtb_testcases_end - __dtb_testcases_begin;
+ u32 size = __dtb_testcases_end - __dtb_testcases_begin;
int rc;
if (!size) {
@@ -1425,10 +1426,14 @@ static int __init unittest_data_add(void)
}
/* creating copy */
- unittest_data = kmemdup(__dtb_testcases_begin, size, GFP_KERNEL);
+ size += FDT_ALIGN_SIZE;
+ unittest_data = kmalloc(size, GFP_KERNEL);
if (!unittest_data)
return -ENOMEM;
+ unittest_data = PTR_ALIGN(unittest_data, FDT_ALIGN_SIZE);
+ memcpy(unittest_data, __dtb_testcases_begin, size);
+
of_fdt_unflatten_tree(unittest_data, NULL, &unittest_data_node);
if (!unittest_data_node) {
pr_warn("%s: No tree to attach; not running tests\n", __func__);
--
Frank Rowand <frank.rowand@xxxxxxxx>
