fanotify: Dont try to open a file descriptor for the overflow event

We should not try to open a file descriptor for the overflow event since this
will always fail.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

1 files changed, 13 insertions, 4 deletions

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index ca54957b1f61..dccd7985e65a 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -110,6 +110,8 @@ static int fill_event_metadata(struct fsnotify_group *group,
                                    struct fanotify_event_metadata *metadata,
                                    struct fsnotify_event *event)
 {
+        int ret = 0;
+
         pr_debug("%s: group=%p metadata=%p event=%p\n", __func__,
                  group, metadata, event);
 
@@ -117,9 +119,15 @@ static int fill_event_metadata(struct fsnotify_group *group,
         metadata->vers = FANOTIFY_METADATA_VERSION;
         metadata->mask = event->mask & FAN_ALL_OUTGOING_EVENTS;
         metadata->pid = pid_vnr(event->tgid);
-        metadata->fd = create_fd(group, event);
+        if (unlikely(event->mask & FAN_Q_OVERFLOW))
+                metadata->fd = FAN_NOFD;
+        else {
+                metadata->fd = create_fd(group, event);
+                if (metadata->fd < 0)
+                        ret = metadata->fd;
+        }
 
-        return metadata->fd;
+        return ret;
 }
 
 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
@@ -261,7 +269,7 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
         if (ret < 0)
                 goto out;
 
-        fd = ret;
+        fd = fanotify_event_metadata.fd;
         ret = prepare_for_access_response(group, event, fd);
         if (ret)
                 goto out_close_fd;
@@ -275,7 +283,8 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
 out_kill_access_response:
         remove_access_response(group, event, fd);
 out_close_fd:
-        sys_close(fd);
+        if (fd != FAN_NOFD)
+                sys_close(fd);
 out:
 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
         if (event->mask & FAN_ALL_PERM_EVENTS) {