The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y git checkout FETCH_HEAD git cherry-pick -x c915d8f5918bea7c3962b09b8884ca128bfd9b0c # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023051351-cross-bunny-a0c7@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:

c915d8f5918b ("inotify: Avoid reporting event with invalid wd") ec165450968b ("memcg, fsnotify: no oom-kill for remote memcg charging") a0a92d261f29 ("fsnotify: move mask out of struct fsnotify_event") d0a6a87e40da ("fanotify: support reporting thread id instead of process id") bdd5a46fe306 ("fanotify: add BUILD_BUG_ON() to count the bits of fanotify constants") 23c9deeb3285 ("fanotify: deprecate uapi FAN_ALL_* constants") a72fd224e37b ("fanotify: simplify handling of FAN_ONDIR") b723a7911d02 ("fanotify: fix collision of internal and uapi mark flags") 96a71f21ef1f ("fanotify: store fanotify_init() flags in group's fanotify_data") d54f4fba889b ("fanotify: add API to attach/detach super block mark")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c915d8f5918bea7c3962b09b8884ca128bfd9b0c Mon Sep 17 00:00:00 2001 From: Jan Kara jack@suse.cz Date: Mon, 24 Apr 2023 18:32:19 +0200 Subject: [PATCH] inotify: Avoid reporting event with invalid wd

When inotify_freeing_mark() races with inotify_handle_inode_event() it can happen that inotify_handle_inode_event() sees that i_mark->wd got already reset to -1 and reports this value to userspace which can confuse the inotify listener. Avoid the problem by validating that wd is sensible (and pretend the mark got removed before the event got generated otherwise).

CC: stable@vger.kernel.org Fixes: 7e790dd5fc93 ("inotify: fix error paths in inotify_update_watch") Message-Id: 20230424163219.9250-1-jack@suse.cz Reported-by: syzbot+4a06d4373fd52f0b2f9c@syzkaller.appspotmail.com Reviewed-by: Amir Goldstein amir73il@gmail.com Signed-off-by: Jan Kara jack@suse.cz

diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c index 49cfe2ae6d23..993375f0db67 100644 --- a/fs/notify/inotify/inotify_fsnotify.c +++ b/fs/notify/inotify/inotify_fsnotify.c @@ -65,7 +65,7 @@ int inotify_handle_inode_event(struct fsnotify_mark *inode_mark, u32 mask, struct fsnotify_event *fsn_event; struct fsnotify_group *group = inode_mark->group; int ret; - int len = 0; + int len = 0, wd; int alloc_len = sizeof(struct inotify_event_info); struct mem_cgroup *old_memcg;

@@ -80,6 +80,13 @@ int inotify_handle_inode_event(struct fsnotify_mark *inode_mark, u32 mask, i_mark = container_of(inode_mark, struct inotify_inode_mark, fsn_mark);

+ /* + * We can be racing with mark being detached. Don't report event with + * invalid wd. + */ + wd = READ_ONCE(i_mark->wd); + if (wd == -1) + return 0; /* * Whoever is interested in the event, pays for the allocation. Do not * trigger OOM killer in the target monitoring memcg as it may have @@ -110,7 +117,7 @@ int inotify_handle_inode_event(struct fsnotify_mark *inode_mark, u32 mask, fsn_event = &event->fse; fsnotify_init_event(fsn_event); event->mask = mask; - event->wd = i_mark->wd; + event->wd = wd; event->sync_cookie = cookie; event->name_len = len; if (len)