[PATCH v3] IOMUX: Fix buffer overflow in iomux_replace_device()

[Peter Robinson]

On Mon, Apr 26, 2021 at 12:08 AM Yuichiro Goto <goto at k-tech.co.jp> wrote:
>
> Use of strcat() against an uninitialized buffer would lead
> to buffer overflow. This patch fixes it.
>
> Fixes: 694cd5618c ("IOMUX: Introduce iomux_replace_device()")
> Signed-off-by: Yuichiro Goto <goto at k-tech.co.jp>
> Cc: Peter Robinson <pbrobinson at gmail.com>
> Cc: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
> Cc: Nicolas Saenz Julienne <nsaenzjulienne at suse.de>

Tested-by: Peter Robinson <pbrobinson at gmail.com>
On a RPi2/RPi3 and Cubieboard

> ---
>
> Changes for v3:
> - Add a Fixes tag in commit message
> - Refactor the patch per suggestion from Andy Shevchenko
>
> Changes for v2:
> - Add "IOMUX" in title
>
>  common/iomux.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/common/iomux.c b/common/iomux.c
> index b9088aa3b5..c428f7110a 100644
> --- a/common/iomux.c
> +++ b/common/iomux.c
> @@ -158,8 +158,12 @@ int iomux_replace_device(const int console, const char *old, const char *new)
>                         return -ENOMEM;
>                 }
>
> -               strcat(tmp, ",");
> -               strcat(tmp, name);
> +               if (arg) {
> +                       strcat(tmp, ",");
> +                       strcat(tmp, name);
> +               }
> +               else
> +                       strcpy(tmp, name);
>
>                 arg = tmp;
>                 size = strlen(tmp) + 1;
> --
> 2.17.1
>