From 66db3feb486c01349f767b98ebb10b0c3d2d021b Mon Sep 17 00:00:00 2001
From: CQ Tang <cq.tang@intel.com>
Date: Mon, 18 Mar 2013 11:02:21 -0400
Subject: [PATCH] x86-64: Fix the failure case in copy_user_handle_tail()
The increment of "to" in copy_user_handle_tail() will have incremented
before a failure has been noted. This causes us to skip a byte in the
failure case.
Only do the increment when assured there is no failure.
Signed-off-by: CQ Tang <cq.tang@intel.com>
Link: http://lkml.kernel.org/r/20130318150221.8439.993.stgit@phlsvslse11.ph.intel.com
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org>
---
arch/x86/lib/usercopy_64.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
index 05928aae911e..906fea315791 100644
--- a/arch/x86/lib/usercopy_64.c
+++ b/arch/x86/lib/usercopy_64.c
@@ -74,10 +74,10 @@ copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest)
char c;
unsigned zero_len;
- for (; len; --len) {
+ for (; len; --len, to++) {
if (__get_user_nocheck(c, from++, sizeof(char)))
break;
- if (__put_user_nocheck(c, to++, sizeof(char)))
+ if (__put_user_nocheck(c, to, sizeof(char)))
break;
}
--
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