staging: lustre: echo_copy.._lsm() dereferences userland pointers directly

commit 9225c0b7 upstream.

missing get_user()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/staging/lustre/lustre/obdecho/echo_client.c

@@ -1380,6 +1380,7 @@ static int
 echo_copyout_lsm (struct lov_stripe_md *lsm, void *_ulsm, int ulsm_nob)
 {
 	struct lov_stripe_md *ulsm = _ulsm;
+	struct lov_oinfo **p;
 	int nob, i;
 
 	nob = offsetof (struct lov_stripe_md, lsm_oinfo[lsm->lsm_stripe_count]);
@@ -1389,9 +1390,10 @@ echo_copyout_lsm (struct lov_stripe_md *lsm, void *_ulsm, int ulsm_nob)
 	if (copy_to_user (ulsm, lsm, sizeof(*ulsm)))
 		return (-EFAULT);
 
-	for (i = 0; i < lsm->lsm_stripe_count; i++) {
-		if (copy_to_user (ulsm->lsm_oinfo[i], lsm->lsm_oinfo[i],
-				      sizeof(lsm->lsm_oinfo[0])))
+	for (i = 0, p = lsm->lsm_oinfo; i < lsm->lsm_stripe_count; i++, p++) {
+		struct lov_oinfo __user *up;
+		if (get_user(up, ulsm->lsm_oinfo + i) ||
+		    copy_to_user(up, *p, sizeof(struct lov_oinfo)))
 			return (-EFAULT);
 	}
 	return 0;
@@ -1399,9 +1401,10 @@ echo_copyout_lsm (struct lov_stripe_md *lsm, void *_ulsm, int ulsm_nob)
 
 static int
 echo_copyin_lsm (struct echo_device *ed, struct lov_stripe_md *lsm,
-		 void *ulsm, int ulsm_nob)
+		struct lov_stripe_md __user *ulsm, int ulsm_nob)
 {
 	struct echo_client_obd *ec = ed->ed_ec;
+	struct lov_oinfo **p;
 	int		     i;
 
 	if (ulsm_nob < sizeof (*lsm))
@@ -1417,11 +1420,10 @@ echo_copyin_lsm (struct echo_device *ed, struct lov_stripe_md *lsm,
 		return (-EINVAL);
 
 
-	for (i = 0; i < lsm->lsm_stripe_count; i++) {
-		if (copy_from_user(lsm->lsm_oinfo[i],
-				       ((struct lov_stripe_md *)ulsm)-> \
-				       lsm_oinfo[i],
-				       sizeof(lsm->lsm_oinfo[0])))
+	for (i = 0, p = lsm->lsm_oinfo; i < lsm->lsm_stripe_count; i++, p++) {
+		struct lov_oinfo __user *up;
+		if (get_user(up, ulsm->lsm_oinfo + i) ||
+		    copy_from_user(*p, up, sizeof(struct lov_oinfo)))
 			return (-EFAULT);
 	}
 	return (0);