On Tue, Jun 29, 2021 at 10:11 PM Gabriel Krisman Bertazi
<krisman@xxxxxxxxxxxxx> wrote:
>
> 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")
> Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
>
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> Changes since v2:
> - Do check for hashed events inside the insert hook (Amir)
> ---
> fs/notify/fanotify/fanotify.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 057abd2cf887..310246f8d3f1 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);
> --
> 2.32.0
>
