Patch "fsnotify: Don't insert unmergeable events in hashtable" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    fsnotify: Don't insert unmergeable events in hashtable

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     fsnotify-don-t-insert-unmergeable-events-in-hashtabl.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 11f9bfad82b5d7745b4c616a4a82e2572f940939
Author: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
Date:   Mon Oct 25 16:27:19 2021 -0300

    fsnotify: Don't insert unmergeable events in hashtable
    
    [ Upstream commit cc53b55f697fe5aa98bdbfdfe67c6401da242155 ]
    
    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: 94e00d28a680 ("fsnotify: use hash table for faster events merge")
    Link: https://lore.kernel.org/r/20211025192746.66445-5-krisman@xxxxxxxxxxxxx
    Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
    Reviewed-by: Jan Kara <jack@xxxxxxx>
    Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
    Signed-off-by: Jan Kara <jack@xxxxxxx>
    Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 057abd2cf8875..310246f8d3f19 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -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);