[PATCH next] drivers/of/overlay: Use memcpy() to copy known length strings

[PATCH next] drivers/of/overlay: Use memcpy() to copy known length strings

[david.laight.linux]

From: David Laight <david.laight.linux@gmail.com>

The lengths have been used for the kzalloc(), use the same ones for the copy.

Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
This is one of a group of patches that remove potentially unbounded
strcpy() calls.

They are mostly replaced by strscpy() or, when strlen() has just been
called, with memcpy() (usually including the '\0').

Calls with copy string literals into arrays are left unchanged.
They are safe and easily detected as such.

The changes were made by getting the compiler to detect the calls and
then fixing the code by hand.

Note that all the changes are only compile tested.

Some Makefiles were changed to allow files to contain strcpy().
As well as 'difficult to fix' files, this included 'show' functions
as they really need to use sysfs_emit() or seq_printf().

All the patches are being sent individually to avoid very long cc lists.
Apologies for the terse commit messages and likely unexpected tags.
(There are about 100 patches in total.)

 drivers/of/overlay.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index c1c5686fc7b1..656867009514 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -258,8 +258,8 @@ static struct property *dup_and_fixup_symbol_prop(
 	if (!new_prop->name || !new_prop->value)
 		goto err_free_new_prop;
 
-	strcpy(new_prop->value, target_path);
-	strcpy(new_prop->value + target_path_len, path_tail);
+	memcpy(new_prop->value, target_path, target_path_len);
+	memcpy(new_prop->value + target_path_len, path_tail, path_tail_len);
 
 	of_property_set_flag(new_prop, OF_DYNAMIC);
 
-- 
2.39.5

Re: [PATCH next] drivers/of/overlay: Use memcpy() to copy known length strings

[Rob Herring]

On Mon, Jun 8, 2026 at 4:55 AM <david.laight.linux@gmail.com> wrote:
>
> From: David Laight <david.laight.linux@gmail.com>
>
> The lengths have been used for the kzalloc(), use the same ones for the copy.

This doesn't answer why we are doing this. Only the below which gets
removed on commit provides the reasoning.

>
> Signed-off-by: David Laight <david.laight.linux@gmail.com>
> ---
> This is one of a group of patches that remove potentially unbounded
> strcpy() calls.
>
> They are mostly replaced by strscpy() or, when strlen() has just been
> called, with memcpy() (usually including the '\0').
>
> Calls with copy string literals into arrays are left unchanged.
> They are safe and easily detected as such.
>
> The changes were made by getting the compiler to detect the calls and
> then fixing the code by hand.
>
> Note that all the changes are only compile tested.
>
> Some Makefiles were changed to allow files to contain strcpy().
> As well as 'difficult to fix' files, this included 'show' functions
> as they really need to use sysfs_emit() or seq_printf().
>
> All the patches are being sent individually to avoid very long cc lists.
> Apologies for the terse commit messages and likely unexpected tags.
> (There are about 100 patches in total.)
>
>  drivers/of/overlay.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
> index c1c5686fc7b1..656867009514 100644
> --- a/drivers/of/overlay.c
> +++ b/drivers/of/overlay.c
> @@ -258,8 +258,8 @@ static struct property *dup_and_fixup_symbol_prop(
>         if (!new_prop->name || !new_prop->value)
>                 goto err_free_new_prop;
>
> -       strcpy(new_prop->value, target_path);
> -       strcpy(new_prop->value + target_path_len, path_tail);
> +       memcpy(new_prop->value, target_path, target_path_len);
> +       memcpy(new_prop->value + target_path_len, path_tail, path_tail_len);
>
>         of_property_set_flag(new_prop, OF_DYNAMIC);
>
> --
> 2.39.5
>

Re: [PATCH next] drivers/of/overlay: Use memcpy() to copy known length strings

[David Laight]

On Mon, 8 Jun 2026 12:35:06 -0500
Rob Herring <robh@kernel.org> wrote:

> On Mon, Jun 8, 2026 at 4:55 AM <david.laight.linux@gmail.com> wrote:
> >
> > From: David Laight <david.laight.linux@gmail.com>
> >
> > The lengths have been used for the kzalloc(), use the same ones for the copy.  
> 
> This doesn't answer why we are doing this. Only the below which gets
> removed on commit provides the reasoning.

I will resend with an extra line (or two) of description above the ---.

(I was using -m 'text' to add the commit message and using same text for
equivalent changes to multiple files - seem to have got caught out!)

-- David

> 
> >
> > Signed-off-by: David Laight <david.laight.linux@gmail.com>
> > ---
> > This is one of a group of patches that remove potentially unbounded
> > strcpy() calls.
> >
> > They are mostly replaced by strscpy() or, when strlen() has just been
> > called, with memcpy() (usually including the '\0').
> >
> > Calls with copy string literals into arrays are left unchanged.
> > They are safe and easily detected as such.
> >
> > The changes were made by getting the compiler to detect the calls and
> > then fixing the code by hand.
> >
> > Note that all the changes are only compile tested.
> >
> > Some Makefiles were changed to allow files to contain strcpy().
> > As well as 'difficult to fix' files, this included 'show' functions
> > as they really need to use sysfs_emit() or seq_printf().
> >
> > All the patches are being sent individually to avoid very long cc lists.
> > Apologies for the terse commit messages and likely unexpected tags.
> > (There are about 100 patches in total.)
> >
> >  drivers/of/overlay.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
> > index c1c5686fc7b1..656867009514 100644
> > --- a/drivers/of/overlay.c
> > +++ b/drivers/of/overlay.c
> > @@ -258,8 +258,8 @@ static struct property *dup_and_fixup_symbol_prop(
> >         if (!new_prop->name || !new_prop->value)
> >                 goto err_free_new_prop;
> >
> > -       strcpy(new_prop->value, target_path);
> > -       strcpy(new_prop->value + target_path_len, path_tail);
> > +       memcpy(new_prop->value, target_path, target_path_len);
> > +       memcpy(new_prop->value + target_path_len, path_tail, path_tail_len);
> >
> >         of_property_set_flag(new_prop, OF_DYNAMIC);
> >
> > --
> > 2.39.5
> >