Re: [PATCH v2 1/1] of: unittest: overlay: ensure proper alignment of copied FDT
On 4/8/21 7:43 AM, frowand.l...@gmail.com wrote:
> From: Frank Rowand
>
> 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-li...@roeck-us.net/
>
> Reported-by: Guenter Roeck
> Signed-off-by: Frank Rowand
>
> ---
>
> Please review carefully, I am not yet fully awake...
>
> changes since version 1:
> - use pointer from kmalloc() for kfree() instead of using pointer that
> has been modified for FDT alignment
>
> drivers/of/of_private.h | 2 ++
> drivers/of/overlay.c| 28 +---
> drivers/of/unittest.c | 12 +---
> 3 files changed, 28 insertions(+), 14 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
> +
Wasn't there a define for that elsewhere ?
> /**
> * 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..e0397d70d531 100644
> --- a/drivers/of/overlay.c
> +++ b/drivers/of/overlay.c
> @@ -57,7 +57,7 @@ struct fragment {
> * struct overlay_changeset
> * @id: changeset identifier
> * @ovcs_list: list on which we are located
> - * @fdt: FDT that was unflattened to create @overlay_tree
> + * @fdt: base of memory allocated to hold aligned FDT that was
> unflattened to create @overlay_tree
> * @overlay_tree:expanded device tree that contains the fragment nodes
> * @count: count of fragment structures
> * @fragments: fragment nodes in the overlay expanded device
> tree
> @@ -719,8 +719,8 @@ static struct device_node *find_target(struct device_node
> *info_node)
> /**
> * init_overlay_changeset() - initialize overlay changeset from overlay tree
> * @ovcs:Overlay changeset to build
> - * @fdt: the FDT that was unflattened to create @tree
> - * @tree:Contains all the overlay fragments and overlay fixup nodes
> + * @fdt: base of memory allocated to hold aligned FDT that was
> unflattened to create @tree
> + * @tree:Contains the overlay fragments and overlay fixup nodes
> *
> * Initialize @ovcs. Populate @ovcs->fragments with node information from
> * the top level of @tree. The relevant top level nodes are the fragment
> @@ -873,7 +873,8 @@ static void free_overlay_changeset(struct
> overlay_changeset *ovcs)
> * internal documentation
> *
> * of_overlay_apply() - Create and apply an overlay changeset
> - * @fdt: the FDT that was unflattened to create @tree
> + * @fdt_align: the FDT that was unflattened to create @tree, aligned
> + * @fdt: base of memory allocated to hold *@fdt_align
> * @tree:Expanded overlay device tree
> * @ovcs_id: Pointer to overlay changeset id
> *
> @@ -912,8 +913,8 @@ static void free_overlay_changeset(struct
> overlay_changeset *ovcs)
> * id is returned to *ovcs_id.
> */
>
> -static int of_overlay_apply(const void *fdt, struct device_node *tree,
> - int *ovcs_id)
> +static int of_overlay_apply(const void *fdt_align, const void *fdt,
> + struct device_node *tree, int *ovcs_id)
Is fdt_align used anywhere in this function ?
On a side note, it seems messy that of_overlay_apply() calls kfree on error.
That would probably be better handled in the calling code.
> {
> struct overlay_changeset *ovcs;
> int ret = 0, ret_revert, ret_tmp;
> @@ -953,7 +954,7 @@ static int of_overlay_apply(const void *fdt, struct
> device_node *tree,
> /*
>* after overlay_notify(), ovcs->overlay_tree related pointers may have
>* leaked to drivers, so can not kfree() tree, aka ovcs->overlay_tree;
> - * and can not free fdt, aka ovcs->fdt
> + * and can not free memory containing aligned fdt, aka ovcs->fdt
fdt doesn't point to the aligned fdt, though. ovcs->fdt is the allocated fdt.
>*/
> ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY);
> if (ret) {
> @@ -1014,7 +1015,8 @@ 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;
> + void *new_fdt_align;
>
Re: [PATCH v2 1/1] of: unittest: overlay: ensure proper alignment of copied FDT
Hi Rob,
I had a git hiccup, this is not the version I meant to send. v3 coming shortly.
-Frank
On 4/8/21 9:43 AM, frowand.l...@gmail.com wrote:
> From: Frank Rowand
>
> 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-li...@roeck-us.net/
>
> Reported-by: Guenter Roeck
> Signed-off-by: Frank Rowand
>
> ---
>
> Please review carefully, I am not yet fully awake...
>
> changes since version 1:
> - use pointer from kmalloc() for kfree() instead of using pointer that
> has been modified for FDT alignment
>
> drivers/of/of_private.h | 2 ++
> drivers/of/overlay.c| 28 +---
> drivers/of/unittest.c | 12 +---
> 3 files changed, 28 insertions(+), 14 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..e0397d70d531 100644
> --- a/drivers/of/overlay.c
> +++ b/drivers/of/overlay.c
> @@ -57,7 +57,7 @@ struct fragment {
> * struct overlay_changeset
> * @id: changeset identifier
> * @ovcs_list: list on which we are located
> - * @fdt: FDT that was unflattened to create @overlay_tree
> + * @fdt: base of memory allocated to hold aligned FDT that was
> unflattened to create @overlay_tree
> * @overlay_tree:expanded device tree that contains the fragment nodes
> * @count: count of fragment structures
> * @fragments: fragment nodes in the overlay expanded device
> tree
> @@ -719,8 +719,8 @@ static struct device_node *find_target(struct device_node
> *info_node)
> /**
> * init_overlay_changeset() - initialize overlay changeset from overlay tree
> * @ovcs:Overlay changeset to build
> - * @fdt: the FDT that was unflattened to create @tree
> - * @tree:Contains all the overlay fragments and overlay fixup nodes
> + * @fdt: base of memory allocated to hold aligned FDT that was
> unflattened to create @tree
> + * @tree:Contains the overlay fragments and overlay fixup nodes
> *
> * Initialize @ovcs. Populate @ovcs->fragments with node information from
> * the top level of @tree. The relevant top level nodes are the fragment
> @@ -873,7 +873,8 @@ static void free_overlay_changeset(struct
> overlay_changeset *ovcs)
> * internal documentation
> *
> * of_overlay_apply() - Create and apply an overlay changeset
> - * @fdt: the FDT that was unflattened to create @tree
> + * @fdt_align: the FDT that was unflattened to create @tree, aligned
> + * @fdt: base of memory allocated to hold *@fdt_align
> * @tree:Expanded overlay device tree
> * @ovcs_id: Pointer to overlay changeset id
> *
> @@ -912,8 +913,8 @@ static void free_overlay_changeset(struct
> overlay_changeset *ovcs)
> * id is returned to *ovcs_id.
> */
>
> -static int of_overlay_apply(const void *fdt, struct device_node *tree,
> - int *ovcs_id)
> +static int of_overlay_apply(const void *fdt_align, const void *fdt,
> + struct device_node *tree, int *ovcs_id)
> {
> struct overlay_changeset *ovcs;
> int ret = 0, ret_revert, ret_tmp;
> @@ -953,7 +954,7 @@ static int of_overlay_apply(const void *fdt, struct
> device_node *tree,
> /*
>* after overlay_notify(), ovcs->overlay_tree related pointers may have
>* leaked to drivers, so can not kfree() tree, aka ovcs->overlay_tree;
> - * and can not free fdt, aka ovcs->fdt
> + * and can not free memory containing aligned fdt, aka ovcs->fdt
>*/
> ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY);
> if (ret) {
> @@ -1014,7 +1015,8 @@ 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;
> + void *new_fdt_align;
> int ret;
> u32 size;
> struct device_node *overlay_root;
> @@ -1036,18 +1038,22 @@ int of_overlay_fdt_apply(const void *overlay_fdt, u32
> overlay_fdt_size,
>* Must create permanent copy of
[PATCH v2 1/1] of: unittest: overlay: ensure proper alignment of copied FDT
From: Frank Rowand
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-li...@roeck-us.net/
Reported-by: Guenter Roeck
Signed-off-by: Frank Rowand
---
Please review carefully, I am not yet fully awake...
changes since version 1:
- use pointer from kmalloc() for kfree() instead of using pointer that
has been modified for FDT alignment
drivers/of/of_private.h | 2 ++
drivers/of/overlay.c| 28 +---
drivers/of/unittest.c | 12 +---
3 files changed, 28 insertions(+), 14 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..e0397d70d531 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -57,7 +57,7 @@ struct fragment {
* struct overlay_changeset
* @id:changeset identifier
* @ovcs_list: list on which we are located
- * @fdt: FDT that was unflattened to create @overlay_tree
+ * @fdt: base of memory allocated to hold aligned FDT that was
unflattened to create @overlay_tree
* @overlay_tree: expanded device tree that contains the fragment nodes
* @count: count of fragment structures
* @fragments: fragment nodes in the overlay expanded device tree
@@ -719,8 +719,8 @@ static struct device_node *find_target(struct device_node
*info_node)
/**
* init_overlay_changeset() - initialize overlay changeset from overlay tree
* @ovcs: Overlay changeset to build
- * @fdt: the FDT that was unflattened to create @tree
- * @tree: Contains all the overlay fragments and overlay fixup nodes
+ * @fdt: base of memory allocated to hold aligned FDT that was
unflattened to create @tree
+ * @tree: Contains the overlay fragments and overlay fixup nodes
*
* Initialize @ovcs. Populate @ovcs->fragments with node information from
* the top level of @tree. The relevant top level nodes are the fragment
@@ -873,7 +873,8 @@ static void free_overlay_changeset(struct overlay_changeset
*ovcs)
* internal documentation
*
* of_overlay_apply() - Create and apply an overlay changeset
- * @fdt: the FDT that was unflattened to create @tree
+ * @fdt_align: the FDT that was unflattened to create @tree, aligned
+ * @fdt: base of memory allocated to hold *@fdt_align
* @tree: Expanded overlay device tree
* @ovcs_id: Pointer to overlay changeset id
*
@@ -912,8 +913,8 @@ static void free_overlay_changeset(struct overlay_changeset
*ovcs)
* id is returned to *ovcs_id.
*/
-static int of_overlay_apply(const void *fdt, struct device_node *tree,
- int *ovcs_id)
+static int of_overlay_apply(const void *fdt_align, const void *fdt,
+ struct device_node *tree, int *ovcs_id)
{
struct overlay_changeset *ovcs;
int ret = 0, ret_revert, ret_tmp;
@@ -953,7 +954,7 @@ static int of_overlay_apply(const void *fdt, struct
device_node *tree,
/*
* after overlay_notify(), ovcs->overlay_tree related pointers may have
* leaked to drivers, so can not kfree() tree, aka ovcs->overlay_tree;
-* and can not free fdt, aka ovcs->fdt
+* and can not free memory containing aligned fdt, aka ovcs->fdt
*/
ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY);
if (ret) {
@@ -1014,7 +1015,8 @@ 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;
+ void *new_fdt_align;
int ret;
u32 size;
struct device_node *overlay_root;
@@ -1036,18 +1038,22 @@ 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;
-
