linux-kernel - [PATCH] sparc: copy_from_user() should not return -EFAULT

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Message-ID: <20100105152215.GD5480@osiris.boeblingen.de.ibm.com>
Date:	Tue, 5 Jan 2010 16:22:15 +0100
From:	Heiko Carstens <heiko.carstens@...ibm.com>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Arnd Bergmann <arnd@...db.de>, Ingo Molnar <mingo@...e.hu>,
	David Miller <davem@...emloft.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] sparc: copy_from_user() should not return -EFAULT

Subject: [PATCH] sparc: copy_from_user() should not return -EFAULT

From: Heiko Carstens <heiko.carstens@...ibm.com>

Callers of copy_from_user() expect it to return the number of bytes
it could not copy. In no case it is supposed to return -EFAULT.

In case of a detected buffer overflow just return the requested
length. In addition one could think of a memset that would clear
the size of the target object.

Signed-off-by: Heiko Carstens <heiko.carstens@...ibm.com>
---
 arch/sparc/include/asm/uaccess_32.h |    2 +-
 arch/sparc/include/asm/uaccess_64.h |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/arch/sparc/include/asm/uaccess_32.h
+++ b/arch/sparc/include/asm/uaccess_32.h
@@ -274,7 +274,7 @@ static inline unsigned long copy_from_us
 
 	if (unlikely(sz != -1 && sz < n)) {
 		copy_from_user_overflow();
-		return -EFAULT;
+		return n;
 	}
 
 	if (n && __access_ok((unsigned long) from, n))
--- a/arch/sparc/include/asm/uaccess_64.h
+++ b/arch/sparc/include/asm/uaccess_64.h
@@ -221,8 +221,8 @@ extern unsigned long copy_from_user_fixu
 static inline unsigned long __must_check
 copy_from_user(void *to, const void __user *from, unsigned long size)
 {
-	unsigned long ret = (unsigned long) -EFAULT;
 	int sz = __compiletime_object_size(to);
+	unsigned long ret = size;
 
 	if (likely(sz == -1 || sz >= size)) {
 		ret = ___copy_from_user(to, from, size);
--
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