Hi Kees,
On Thu, Sep 3, 2026 at 4:24 PM Kees Cook <[email protected]> wrote:
>
> find_bad_casts() reports a cast between two randomized structure pointer
> types with inform(), which renders as a "note:". It has done so since
> the plugin was originally added, while using error() freely for attribute
> misuse, UAPI structs, and version mismatches.
>
> Clang's implementation of the same check has always been stricter:
> it rejects such a cast as a full error. There is no reason for the GCC
> side to be effectively silent about the same problem.
>
> Build tested ARCH=x86_64 with CONFIG_RANDSTRUCT_FULL=y and GCC 14.2.0:
> allmodconfig clean, and defconfig clean under three different random
> seeds. A deliberate bad cast is still reported, now as a warning, at the
> correct line and column.
>
> Signed-off-by: Kees Cook <[email protected]>
> ---
> scripts/gcc-plugins/randomize_layout_plugin.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c
> b/scripts/gcc-plugins/randomize_layout_plugin.c
> index e2bd9ba08089..1e66f45fe29b 100644
> --- a/scripts/gcc-plugins/randomize_layout_plugin.c
> +++ b/scripts/gcc-plugins/randomize_layout_plugin.c
> @@ -22,7 +22,7 @@
> #define ORIG_TYPE_NAME(node) \
> (TYPE_NAME(TYPE_MAIN_VARIANT(node)) != NULL_TREE ? ((const unsigned
> char *)IDENTIFIER_POINTER(TYPE_NAME(TYPE_MAIN_VARIANT(node)))) : (const
> unsigned char *)"anonymous")
>
> -#define INFORM(loc, msg, ...) inform(loc, "randstruct: " msg, ##__VA_ARGS__)
> +#define INFORM(loc, msg, ...) warning_at(loc, 0, "randstruct: " msg,
> ##__VA_ARGS__)
Why not make this an error instead of a warning?
-bw
> #define MISMATCH(loc, how, ...) INFORM(loc, "casting between
> randomized structure pointer types (" how "): %qT and %qT\n", __VA_ARGS__)
>
> __visible int plugin_is_GPL_compatible;
> --
> 2.34.1
>
