2022-06-10 15:46:10

by Christophe Leroy

Subject: [PATCH] powerpc/prom_init: Fix build failure with GCC_PLUGIN_STRUCTLEAK_BYREF_ALL and KASAN

When CONFIG_KASAN is selected, we expect prom_init to use __memset()
because it is too early to use memset().

But with CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL, the compiler adds calls
to memset() to clear objects on stack, hence the following failure:

PROMCHK arch/powerpc/kernel/prom_init_check
Error: External symbol 'memset' referenced from prom_init.c
make[2]: *** [arch/powerpc/kernel/Makefile:204 : arch/powerpc/kernel/prom_init_check] Erreur 1

prom_find_machine_type() is called from prom_init() and is called only
once, so lets put compat[] in BSS instead of stack to avoid that.

Signed-off-by: Christophe Leroy <[email protected]>
---
arch/powerpc/kernel/prom_init.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index 04694ec423f6..13d6cb188835 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -2302,7 +2302,7 @@ static void __init prom_init_stdout(void)

static int __init prom_find_machine_type(void)
{
- char compat[256];
+ static char compat[256] __prombss;
int len, i = 0;
#ifdef CONFIG_PPC64
phandle rtas;
--
2.35.3

2022-06-26 00:45:39

by Michael Ellerman

Subject: Re: [PATCH] powerpc/prom_init: Fix build failure with GCC_PLUGIN_STRUCTLEAK_BYREF_ALL and KASAN

On Fri, 10 Jun 2022 17:43:43 +0200, Christophe Leroy wrote:
> When CONFIG_KASAN is selected, we expect prom_init to use __memset()
> because it is too early to use memset().
>
> But with CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL, the compiler adds calls
> to memset() to clear objects on stack, hence the following failure:
>
> PROMCHK arch/powerpc/kernel/prom_init_check
> Error: External symbol 'memset' referenced from prom_init.c
> make[2]: *** [arch/powerpc/kernel/Makefile:204 : arch/powerpc/kernel/prom_init_check] Erreur 1
>
> [...]

Applied to powerpc/fixes.

[1/1] powerpc/prom_init: Fix build failure with GCC_PLUGIN_STRUCTLEAK_BYREF_ALL and KASAN
https://git.kernel.org/powerpc/c/ca5dabcff1df6bc8c413922b5fa63cc602858803

cheers