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SubjectRe: [PATCH] arm: decompressor: mark error() as __noreturn
On Wed, Apr 04, 2018 at 03:34:06PM -0700, Kees Cook wrote:
> On Wed, Apr 4, 2018 at 5:30 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> > gcc complains about fortify_panic() possibly returning:
> >
> > arch/arm/boot/compressed/misc.c: In function 'fortify_panic':
> > arch/arm/boot/compressed/misc.c:167:1: error: 'noreturn' function does return [-Werror]
> >
> > This annotates the error() function as __noreturn, which lets gcc
> > see in all configurations that it fortify_panic() cannot return either.
> >
> > Fixes: ee333554fed5 ("ARM: 8749/1: Kconfig: Add ARCH_HAS_FORTIFY_SOURCE")
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>
> Acked-by: Kees Cook <keescook@chromium.org>

I'd actually prefer a more robust solution to this - error() is used
in different files, each with their own separate prototype, which is
error-prone. The same goes for a few other variables. The following
is IMHO a more complete (and thus larger) patch:

arch/arm/boot/compressed/decompress.c | 5 +----
arch/arm/boot/compressed/misc.c | 2 +-
arch/arm/boot/compressed/misc.h | 10 ++++++++++
3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/arch/arm/boot/compressed/decompress.c b/arch/arm/boot/compressed/decompress.c
index a2ac3fe7dbf8..c16c1829a5e4 100644
--- a/arch/arm/boot/compressed/decompress.c
+++ b/arch/arm/boot/compressed/decompress.c
@@ -6,10 +6,7 @@
#include <linux/stddef.h> /* for NULL */
#include <linux/linkage.h>
#include <asm/string.h>
-
-extern unsigned long free_mem_ptr;
-extern unsigned long free_mem_end_ptr;
-extern void error(char *);
+#include "misc.h"

#define STATIC static
#define STATIC_RW_DATA /* non-static please */
diff --git a/arch/arm/boot/compressed/misc.c b/arch/arm/boot/compressed/misc.c
index a3ded2a64b32..e94c84dded6c 100644
--- a/arch/arm/boot/compressed/misc.c
+++ b/arch/arm/boot/compressed/misc.c
@@ -22,9 +22,9 @@ unsigned int __machine_arch_type;
#include <linux/compiler.h> /* for inline */
#include <linux/types.h>
#include <linux/linkage.h>
+#include "misc.h"

static void putstr(const char *ptr);
-extern void error(char *x);

#include CONFIG_UNCOMPRESS_INCLUDE

diff --git a/arch/arm/boot/compressed/misc.h b/arch/arm/boot/compressed/misc.h
new file mode 100644
index 000000000000..c958dccd1d97
--- /dev/null
+++ b/arch/arm/boot/compressed/misc.h
@@ -0,0 +1,10 @@
+#ifndef MISC_H
+#define MISC_H
+
+#include <linux/compiler.h>
+
+void error(char *x) __noreturn;
+extern unsigned long free_mem_ptr;
+extern unsigned long free_mem_end_ptr;
+
+#endif

--
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