[PATCH 1/4] microblaze: uaccess: Zero out destination on failed get_user()

["Thomas Weißschuh" <linux@weissschuh.net>]

On failure get_user() is supposed to zero out the destination variable.
This is documented in the kdoc of the microblaze get_user()
implementation and validated in lib/tests/usercopy_kunit.c.

Currently that zeroing is missing.

Add it.

Fixes: 0d6de9532663 ("microblaze_mmu_v2: uaccess MMU update")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 arch/microblaze/include/asm/uaccess.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/microblaze/include/asm/uaccess.h b/arch/microblaze/include/asm/uaccess.h
index afa0dd8d013f..77203af255e5 100644
--- a/arch/microblaze/include/asm/uaccess.h
+++ b/arch/microblaze/include/asm/uaccess.h
@@ -95,7 +95,8 @@ extern long __user_bad(void);
 #define get_user(x, ptr) ({				\
 	const typeof(*(ptr)) __user *__gu_ptr = (ptr);	\
 	access_ok(__gu_ptr, sizeof(*__gu_ptr)) ?	\
-		__get_user(x, __gu_ptr) : -EFAULT;	\
+		__get_user(x, __gu_ptr) :		\
+		((x) = 0, -EFAULT);			\
 })
 
 #define __get_user(x, ptr)						\

-- 
2.55.0