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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>
This commit is contained in:
CQ Tang 2013-03-18 11:02:21 -04:00 committed by H. Peter Anvin
parent a937536b86
commit 66db3feb48
1 changed files with 2 additions and 2 deletions
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4
arch/x86/lib/usercopy_64.c
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@ -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;
}