[PATCH AUTOSEL 5.4 10/27] powerpc/prom_init: Fix build failure with GCC_PLUGIN_STRUCTLEAK_BYREF_ALL and KASAN

Sasha Levin
2022-06-28T02:31:01Z

From: Christophe Leroy <christophe.leroy@csgroup.eu>

[ Upstream commit ca5dabcff1df6bc8c413922b5fa63cc602858803 ]

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 <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/3802811f7cf94f730be44688539c01bba3a3b5c0.1654875808.git.christophe.leroy@csgroup.eu
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 7f4e2c031a9a..0391b3225970 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -2237,7 +2237,7 @@ 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;
--
2.35.1