Commit cc53b55f authored Oct 25, 2021 by Gabriel Krisman Bertazi Committed by Jan Kara Oct 27, 2021

fsnotify: Don't insert unmergeable events in hashtable

Some events, like the overflow event, are not mergeable, so they are not
hashed.  But, when failing inside fsnotify_add_event for lack of space,
fsnotify_add_event() still calls the insert hook, which adds the
overflow event to the merge list.  Add a check to prevent any kind of
unmergeable event to be inserted in the hashtable.

Fixes: 94e00d28 ("fsnotify: use hash table for faster events merge")
Link: https://lore.kernel.org/r/20211025192746.66445-5-krisman@collabora.com


Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>

parent dabe729d

fs/notify/fanotify/fanotify.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -702,6 +702,9 @@ static void fanotify_insert_event(struct fsnotify_group *group,

		assert_spin_locked(&group->notification_lock);

		if (!fanotify_is_hashed_event(event->mask))
		return;

		pr_debug("%s: group=%p event=%p bucket=%u\n", __func__,
		group, event, bucket);

		@@ -779,8 +782,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,

		fsn_event = &event->fse;
		ret = fsnotify_add_event(group, fsn_event, fanotify_merge,
		fanotify_is_hashed_event(mask) ?
		fanotify_insert_event : NULL);
		fanotify_insert_event);
		if (ret) {
		/* Permission events shouldn't be merged */
		BUG_ON(ret == 1 && mask & FANOTIFY_PERM_EVENTS);