Re: [PATCH v2 2/5] kconfig: check for out-of-bounds numeric constants

[Nicolas Schier]

On Tue, Sep 15, 2026 at 10:15:05PM +0100, Julian Braha wrote:
> The Kconfig interpreter internally represents constants as strings, then
> attempts to parse them as 64-bit signed integers for 'int' options, and
> 64-bit unsigned integers for 'hex' options.
> 
> However, there is currently no check that the conversion succeeds, leading
> to failures when the values are actually used. For example:
> 
>   config LARGE_INT
>     int
>     default 10000000000000000000
> 
>   config BUGGED_INT_COMPARISON
>     bool
>     default y if LARGE_INT < 2
> 
> Obviously 10000000000000000000 is larger than 2, but the Kconfig
> interpreter will fallback to comparing the two values with strcmp() after
> the numeric conversion fails, causing the first character, '1', to be
> compared with '2', and giving the wrong result.
> 
> Since none of these out-of-bounds values are used as constants anywhere in
> the tree, we can already make these error out.
> 
> Assisted-by: LLM
> Signed-off-by: Julian Braha <julianbraha@xxxxxxxxx>
> ---
>  scripts/kconfig/menu.c                        | 60 ++++++++++----
>  scripts/kconfig/tests/err_num_bounds/Kconfig  | 79 +++++++++++++++++++
>  .../kconfig/tests/err_num_bounds/__init__.py  | 12 +++
>  .../tests/err_num_bounds/expected_stderr      | 10 +++
>  .../err_num_non_numeric_ref/expected_stderr   | 30 +++----
>  5 files changed, 160 insertions(+), 31 deletions(-)
>  create mode 100644 scripts/kconfig/tests/err_num_bounds/Kconfig
>  create mode 100644 scripts/kconfig/tests/err_num_bounds/__init__.py
>  create mode 100644 scripts/kconfig/tests/err_num_bounds/expected_stderr
> 

Reviewed-by: Nicolas Schier <n.schier@xxxxxxxxx>

-- 
Nicolas