Re: [PATCH] comedi: comedi_bond: Refactor strlcat() to seq_buf in do_dev_config()

[Mariia Nikitash <nikitash.mariiaw@gmail.com>]

Hi!

On Thu, Nov 12, 2026 at 10:39 AM Kees Cook <kees@kernel.org> wrote:
>
> On Sat, Sep 26, 2026 at 11:00:00PM -0700, Mariia Nikitash wrote:
> > From: Bill Wendling <morbo@google.com>
> >
> > do_dev_config() builds a space-separated list of bonded devices in
> > devpriv->name by formatting each "minor:subdev " pair into a temporary
> > stack buffer with snprintf() and appending it with strlcat() in a loop.
> >
> > In preparation for removing the deprecated strlcat() API[1], use struct
> > seq_buf and seq_buf_printf() to format each entry directly into
> > devpriv->name. This avoids repeated rescanning of devpriv->name and
> > eliminates the temporary buffer.
> >
> > Link: https://github.com/KSPP/linux/issues/370 [1]
> > Cc: codemender-patching+linux@google.com
> > Assisted-by: LLM
> > Signed-off-by: Bill Wendling <morbo@google.com>
> > Signed-off-by: Mariia Nikitash <nikitash.mariiaw@gmail.com>
> > ---
> >  drivers/comedi/drivers/comedi_bond.c | 18 ++++++++----------
> >  1 file changed, 8 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/comedi/drivers/comedi_bond.c b/drivers/comedi/drivers/comedi_bond.c
> > index 8e10ecab4f0d..a10cfbd04c72 100644
> > --- a/drivers/comedi/drivers/comedi_bond.c
> > +++ b/drivers/comedi/drivers/comedi_bond.c
> > @@ -39,6 +39,7 @@
> >
> >  #include <linux/module.h>
> >  #include <linux/string.h>
> > +#include <linux/seq_buf.h>
> >  #include <linux/slab.h>
> >  #include <linux/comedi.h>
> >  #include <linux/comedi/comedilib.h>
> > @@ -170,10 +171,11 @@ static int do_dev_config(struct comedi_device *dev, struct comedi_devconfig *it)
> >  {
> >       struct comedi_bond_private *devpriv = dev->private;
> >       DECLARE_BITMAP(devs_opened, COMEDI_NUM_BOARD_MINORS);
> > +     struct seq_buf s;
> >       int i;
> >
> >       memset(&devs_opened, 0, sizeof(devs_opened));
> > -     devpriv->name[0] = 0;
> > +     seq_buf_init(&s, devpriv->name, sizeof(devpriv->name));
> >       /*
> >        * Loop through all comedi devices specified on the command-line,
> >        * building our device list.
> > @@ -250,15 +252,9 @@ static int do_dev_config(struct comedi_device *dev, struct comedi_devconfig *it)
> >                       }
> >                       devpriv->devs = devs;
> >                       devpriv->devs[devpriv->ndevs++] = bdev;
> > -                     {
> > -                             /* Append dev:subdev to devpriv->name */
> > -                             char buf[20];
> > -
> > -                             snprintf(buf, sizeof(buf), "%u:%u ",
> > -                                      bdev->minor, bdev->subdev);
> > -                             strlcat(devpriv->name, buf,
> > -                                     sizeof(devpriv->name));
> > -                     }
> > +
> > +                     /* Append dev:subdev to devpriv->name */
> > +                     seq_buf_printf(&s, "%u:%u ", bdev->minor, bdev->subdev);
> >               }
> >       }
> >
> > @@ -267,6 +263,8 @@ static int do_dev_config(struct comedi_device *dev, struct comedi_devconfig *it)
> >               return -EINVAL;
> >       }
> >
> > +     seq_buf_str(&s);
>
> If this hasn't been applied yet, a v2 with the above changed to the
> now-available seq_buf_terminate() would be nice to have. Either way:
>
> Reviewed-by: Kees Cook <kees@kernel.org>


Thanks for the review! This patch has already been merged, but I'd be
happy to send a follow up patch with seq_buf_terminate() if you'd
like.

>
>
> > +
> >       return 0;
> >  }
> >
> > --
> > 2.43.0
> >
>
> --
> Kees Cook

Best,
Mariia