From: Kees Cook <kees@kernel.org>
To: Suren Baghdasaryan <surenb@google.com>
Cc: Kees Cook <kees@kernel.org>,
Kent Overstreet <kent.overstreet@linux.dev>,
Miguel Ojeda <ojeda@kernel.org>,
kernel test robot <lkp@intel.com>,
Andy Shevchenko <andy@kernel.org>,
Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Bill Wendling <morbo@google.com>,
Justin Stitt <justinstitt@google.com>,
Philipp Reisner <philipp.reisner@linbit.com>,
linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org,
llvm@lists.linux.dev
Subject: [PATCH v2 2/3] compiler.h: Introduce __must_be_byte_array()
Date: Thu, 6 Feb 2025 13:40:07 -0800 [thread overview]
Message-ID: <20250206214014.3567372-2-kees@kernel.org> (raw)
In-Reply-To: <20250206213532.it.087-kees@kernel.org>
In preparation for adding stricter type checking to the str/mem*()
helpers, provide a way to check that a variable is a byte array
via __must_be_byte_array().
Suggested-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Kees Cook <kees@kernel.org>
---
include/linux/compiler.h | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 7af999a131cb..1c0688319435 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -221,7 +221,13 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
#endif /* __CHECKER__ */
/* &a[0] degrades to a pointer: a different type from an array */
-#define __must_be_array(a) __BUILD_BUG_ON_ZERO_MSG(__same_type((a), &(a)[0]), "must be array")
+#define __is_array(a) (!__same_type((a), &(a)[0]))
+#define __must_be_array(a) __BUILD_BUG_ON_ZERO_MSG(!__is_array(a), \
+ "must be array")
+
+#define __is_byte_array(a) (__is_array(a) && sizeof((a)[0]) == 1)
+#define __must_be_byte_array(a) __BUILD_BUG_ON_ZERO_MSG(!__is_byte_array(a), \
+ "must be byte array")
/* Require C Strings (i.e. NUL-terminated) lack the "nonstring" attribute. */
#define __must_be_cstr(p) \
--
2.34.1
next prev parent reply other threads:[~2025-02-06 21:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-06 21:40 [PATCH v2 0/3] string.h: Use ARRAY_SIZE() for memtostr*()/strtomem*() Kees Cook
2025-02-06 21:40 ` [PATCH v2 1/3] compiler.h: Move C string helpers into C-only kernel section Kees Cook
2025-02-06 21:40 ` Kees Cook [this message]
2025-02-06 21:40 ` [PATCH v2 3/3] string.h: Use ARRAY_SIZE() for memtostr*()/strtomem*() Kees Cook
2025-02-06 23:59 ` Suren Baghdasaryan
2025-02-07 1:01 ` Kees Cook
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