From: Kees Cook <kees@kernel.org>
To: Bill Wendling <morbo@google.com>
Cc: Kees Cook <kees@kernel.org>, Vincent Mailhol <mailhol@kernel.org>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Justin Stitt <justinstitt@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: [PATCH 2/2] randstruct: report bad casts as warnings rather than notes
Date: Thu, 3 Sep 2026 16:24:36 -0700 [thread overview]
Message-ID: <20260903232438.60394-2-kees@kernel.org> (raw)
In-Reply-To: <20260903232428.i.323-kees@kernel.org>
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 <kees@kernel.org>
---
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__)
#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
next prev parent reply other threads:[~2026-09-03 23:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-03 23:24 [PATCH 0/2] randstruct: fix container_of() false positives after __mptr removal Kees Cook
2026-09-03 23:24 ` [PATCH 1/2] " Kees Cook
2026-09-03 23:24 ` Kees Cook [this message]
2026-09-04 18:14 ` [PATCH 2/2] randstruct: report bad casts as warnings rather than notes Bill Wendling
2026-09-04 20:24 ` Nathan Chancellor
2026-09-05 0:48 ` Kees Cook
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