Hi Guenter,
On 4/7/21 3:51 PM, frowand.list@xxxxxxxxx wrote:
> 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/
Can you please test this patch?
The most complete coverage will be a config with:
OF_UNITTEST=y
OF_OVERLAY=y
OF_DYNAMIC=y
One path will be missed if you test with:
#OF_OVERLAY=n
#OF_DYNAMIC=n
Thanks!
-Frank
>
> 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__);
>
