From fed474857efbed79cd390d0aee224231ca718f63 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 12 Jan 2012 17:59:46 +0100 Subject: [PATCH] fsnotify: don't BUG in fsnotify_destroy_mark() Removing the parent of a watched file results in "kernel BUG at fs/notify/mark.c:139". To reproduce add "-w /tmp/audit/dir/watched_file" to audit.rules rm -rf /tmp/audit/dir This is caused by fsnotify_destroy_mark() being called without an extra reference taken by the caller. Reported by Francesco Cosoleto here: https://bugzilla.novell.com/show_bug.cgi?id=689860 Fix by removing the BUG_ON and adding a comment about not accessing mark after the iput. Signed-off-by: Miklos Szeredi CC: stable@vger.kernel.org Signed-off-by: Linus Torvalds --- fs/notify/mark.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/notify/mark.c b/fs/notify/mark.c index e14587d55689..f104d565b682 100644 --- a/fs/notify/mark.c +++ b/fs/notify/mark.c @@ -135,9 +135,6 @@ void fsnotify_destroy_mark(struct fsnotify_mark *mark) mark->flags &= ~FSNOTIFY_MARK_FLAG_ALIVE; - /* 1 from caller and 1 for being on i_list/g_list */ - BUG_ON(atomic_read(&mark->refcnt) < 2); - spin_lock(&group->mark_lock); if (mark->flags & FSNOTIFY_MARK_FLAG_INODE) { @@ -181,6 +178,11 @@ void fsnotify_destroy_mark(struct fsnotify_mark *mark) if (inode && (mark->flags & FSNOTIFY_MARK_FLAG_OBJECT_PINNED)) iput(inode); + /* + * We don't necessarily have a ref on mark from caller so the above iput + * may have already destroyed it. Don't touch from now on. + */ + /* * it's possible that this group tried to destroy itself, but this * this mark was simultaneously being freed by inode. If that's the -- 2.20.1