Re: [PATCH linux-next] parisc: use strscpy() to instead of strncpy()

[Helge Deller]

Hi James,

On 12/27/22 13:38, James Bottomley wrote:
> On Fri, 2022-12-23 at 08:55 +0100, Helge Deller wrote:
> > On 12/23/22 03:40, yang.yang29@xxxxxxxxxx wrote:
> > > From: Xu Panda <xu.panda@xxxxxxxxxx>
> > >
> > > The implementation of strscpy() is more robust and safer.
> > > That's now the recommended way to copy NUL-terminated strings.
> >
> > Thanks for your patch, but....
> >
> > > Signed-off-by: Xu Panda <xu.panda@xxxxxxxxxx>
> > > Signed-off-by: Yang Yang <yang.yang29@xxxxxxx>
> > > ---
> > >    drivers/parisc/pdc_stable.c | 9 +++------
> > >    1 file changed, 3 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/drivers/parisc/pdc_stable.c
> > > b/drivers/parisc/pdc_stable.c
> > > index d6af5726ddf3..403bca0021c5 100644
> > > --- a/drivers/parisc/pdc_stable.c
> > > +++ b/drivers/parisc/pdc_stable.c
> > > @@ -274,8 +274,7 @@ pdcspath_hwpath_write(struct pdcspath_entry
> > > *entry, const char *buf, size_t coun
> > >
> > >          /* We'll use a local copy of buf */
> > >          count = min_t(size_t, count, sizeof(in)-1);
> > > -       strncpy(in, buf, count);
> > > -       in[count] = '\0';
> > > +       strscpy(in, buf, count + 1);
> >
> > could you resend it somewhat simplified, e.g.
> > strscpy(in, buf, sizeof(in));
>
> I don't think you can: count is the size of buf, if that's < sizeof(in)
> you've introduced a write beyond end of buffer.  In fact sysfs tends to
> pass pages as buffers, so there's no actual problem, but if that ever
> changed ...

Huh?... he doesn't change "count", so what's wrong with the latest patch?

Helge