Commit 66db3feb authored Mar 18, 2013 by CQ Tang Committed by H. Peter Anvin Mar 18, 2013

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>

parent a937536b

arch/x86/lib/usercopy_64.c

+2 −2

Original line number	Original line	Diff line number	Diff line
	@@ -74,10 +74,10 @@ copy_user_handle_tail(char to, char from, unsigned len, unsigned zerorest)
	char c;		char c;
	unsigned zero_len;		unsigned zero_len;

	for (; len; --len) {		for (; len; --len, to++) {
	if (__get_user_nocheck(c, from++, sizeof(char)))		if (__get_user_nocheck(c, from++, sizeof(char)))
	break;		break;
	if (__put_user_nocheck(c, to++, sizeof(char)))		if (__put_user_nocheck(c, to, sizeof(char)))
	break;		break;
	}		}