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

[David Laight <david.laight.linux@gmail.com>]

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
> >