xen: xenfs: privcmd: check put_user() return code

put_user() may fail.  In this case propagate error code from
privcmd_ioctl_mmap_batch().

Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

1 files changed, 2 insertions, 6 deletions

diff --git a/drivers/xen/xenfs/privcmd.c b/drivers/xen/xenfs/privcmd.c
index f80be7f6eb9..2eb04c84251 100644
--- a/drivers/xen/xenfs/privcmd.c
+++ b/drivers/xen/xenfs/privcmd.c
@@ -266,9 +266,7 @@ static int mmap_return_errors(void *data, void *state)
         xen_pfn_t *mfnp = data;
         struct mmap_batch_state *st = state;
 
-        put_user(*mfnp, st->user++);
-
-        return 0;
+        return put_user(*mfnp, st->user++);
 }
 
 static struct vm_operations_struct privcmd_vm_ops;
@@ -323,10 +321,8 @@ static long privcmd_ioctl_mmap_batch(void __user *udata)
         up_write(&mm->mmap_sem);
 
         if (state.err > 0) {
-                ret = 0;
-
                 state.user = m.arr;
-                traverse_pages(m.num, sizeof(xen_pfn_t),
+                ret = traverse_pages(m.num, sizeof(xen_pfn_t),
                                &pagelist,
                                mmap_return_errors, &state);
         }