4 files changed, 34 insertions, 11 deletions

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 6b9c27548997..63c6bb1f8c4d 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -346,10 +346,16 @@ static __kernel_fsid_t fanotify_get_fsid(struct fsnotify_iter_info *iter_info)
 	__kernel_fsid_t fsid = {};
 
 	fsnotify_foreach_obj_type(type) {
+		struct fsnotify_mark_connector *conn;
+
 		if (!fsnotify_iter_should_report_type(iter_info, type))
 			continue;
 
-		fsid = iter_info->marks[type]->connector->fsid;
+		conn = READ_ONCE(iter_info->marks[type]->connector);
+		/* Mark is just getting destroyed or created? */
+		if (!conn)
+			continue;
+		fsid = conn->fsid;
 		if (WARN_ON_ONCE(!fsid.val[0] && !fsid.val[1]))
 			continue;
 		return fsid;
@@ -408,8 +414,12 @@ static int fanotify_handle_event(struct fsnotify_group *group,
 			return 0;
 	}
 
-	if (FAN_GROUP_FLAG(group, FAN_REPORT_FID))
+	if (FAN_GROUP_FLAG(group, FAN_REPORT_FID)) {
 		fsid = fanotify_get_fsid(iter_info);
+		/* Racing with mark destruction or creation? */
+		if (!fsid.val[0] && !fsid.val[1])
+			return 0;
+	}
 
 	event = fanotify_alloc_event(group, inode, mask, data, data_type,
 				     &fsid);
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 56992b32c6bb..a90bb19dcfa2 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -208,6 +208,7 @@ static int copy_fid_to_user(struct fanotify_event *event, char __user *buf)
 {
 	struct fanotify_event_info_fid info = { };
 	struct file_handle handle = { };
+	unsigned char bounce[FANOTIFY_INLINE_FH_LEN], *fh;
 	size_t fh_len = event->fh_len;
 	size_t len = fanotify_event_info_len(event);
 
@@ -233,7 +234,16 @@ static int copy_fid_to_user(struct fanotify_event *event, char __user *buf)
 
 	buf += sizeof(handle);
 	len -= sizeof(handle);
-	if (copy_to_user(buf, fanotify_event_fh(event), fh_len))
+	/*
+	 * For an inline fh, copy through stack to exclude the copy from
+	 * usercopy hardening protections.
+	 */
+	fh = fanotify_event_fh(event);
+	if (fh_len <= FANOTIFY_INLINE_FH_LEN) {
+		memcpy(bounce, fh, fh_len);
+		fh = bounce;
+	}
+	if (copy_to_user(buf, fh, fh_len))
 		return -EFAULT;
 
 	/* Pad with 0's */
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index e2901fbb9f76..7b53598c8804 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -519,8 +519,10 @@ static int inotify_update_existing_watch(struct fsnotify_group *group,
 	fsn_mark = fsnotify_find_mark(&inode->i_fsnotify_marks, group);
 	if (!fsn_mark)
 		return -ENOENT;
-	else if (create)
-		return -EEXIST;
+	else if (create) {
+		ret = -EEXIST;
+		goto out;
+	}
 
 	i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
 
@@ -548,6 +550,7 @@ static int inotify_update_existing_watch(struct fsnotify_group *group,
 	/* return the wd */
 	ret = i_mark->wd;
 
+out:
 	/* match the get from fsnotify_find_mark() */
 	fsnotify_put_mark(fsn_mark);
 
diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index d593d4269561..22acb0a79b53 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -239,13 +239,13 @@ static void fsnotify_drop_object(unsigned int type, void *objp)
 
 void fsnotify_put_mark(struct fsnotify_mark *mark)
 {
-	struct fsnotify_mark_connector *conn;
+	struct fsnotify_mark_connector *conn = READ_ONCE(mark->connector);
 	void *objp = NULL;
 	unsigned int type = FSNOTIFY_OBJ_TYPE_DETACHED;
 	bool free_conn = false;
 
 	/* Catch marks that were actually never attached to object */
-	if (!mark->connector) {
+	if (!conn) {
 		if (refcount_dec_and_test(&mark->refcnt))
 			fsnotify_final_mark_destroy(mark);
 		return;
@@ -255,10 +255,9 @@ void fsnotify_put_mark(struct fsnotify_mark *mark)
 	 * We have to be careful so that traversals of obj_list under lock can
 	 * safely grab mark reference.
 	 */
-	if (!refcount_dec_and_lock(&mark->refcnt, &mark->connector->lock))
+	if (!refcount_dec_and_lock(&mark->refcnt, &conn->lock))
 		return;
 
-	conn = mark->connector;
 	hlist_del_init_rcu(&mark->obj_list);
 	if (hlist_empty(&conn->list)) {
 		objp = fsnotify_detach_connector_from_object(conn, &type);
@@ -266,7 +265,7 @@ void fsnotify_put_mark(struct fsnotify_mark *mark)
 	} else {
 		__fsnotify_recalc_mask(conn);
 	}
-	mark->connector = NULL;
+	WRITE_ONCE(mark->connector, NULL);
 	spin_unlock(&conn->lock);
 
 	fsnotify_drop_object(type, objp);
@@ -620,7 +619,7 @@ restart:
 	/* mark should be the last entry.  last is the current last entry */
 	hlist_add_behind_rcu(&mark->obj_list, &last->obj_list);
 added:
-	mark->connector = conn;
+	WRITE_ONCE(mark->connector, conn);
 out_err:
 	spin_unlock(&conn->lock);
 	spin_unlock(&mark->lock);
@@ -808,6 +807,7 @@ void fsnotify_init_mark(struct fsnotify_mark *mark,
 	refcount_set(&mark->refcnt, 1);
 	fsnotify_get_group(group);
 	mark->group = group;
+	WRITE_ONCE(mark->connector, NULL);
 }
 
 /*