From 4855bd255f9fb429d296dc3c620f1b563d20353e Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sat, 10 Sep 2016 16:50:00 -0400
Subject: [PATCH] arm64: don't zero in __copy_from_user{,_inatomic}
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
arch/arm64/include/asm/uaccess.h | 10 ++++++----
arch/arm64/lib/copy_from_user.S | 7 +------
2 files changed, 7 insertions(+), 10 deletions(-)
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index c47257c91b77e..bcaf6fba1b65b 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -278,14 +278,16 @@ static inline unsigned long __must_check __copy_to_user(void __user *to, const v
static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
{
+ unsigned long res = n;
kasan_check_write(to, n);
if (access_ok(VERIFY_READ, from, n)) {
check_object_size(to, n, false);
- n = __arch_copy_from_user(to, from, n);
- } else /* security hole - plug it */
- memset(to, 0, n);
- return n;
+ res = __arch_copy_from_user(to, from, n);
+ }
+ if (unlikely(res))
+ memset(to + (n - res), 0, res);
+ return res;
}
static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S
index 0b90497d4424c..4fd67ea03bb05 100644
--- a/arch/arm64/lib/copy_from_user.S
+++ b/arch/arm64/lib/copy_from_user.S
@@ -79,11 +79,6 @@ ENDPROC(__arch_copy_from_user)
.section .fixup,"ax"
.align 2
-9998:
- sub x0, end, dst
-9999:
- strb wzr, [dst], #1 // zero remaining buffer space
- cmp dst, end
- b.lo 9999b
+9998: sub x0, end, dst // bytes not copied
ret
.previous