On Tue, Jul 10, 2018 at 6:02 AM Jan Kara <jack@xxxxxxx> wrote: > When an inode is tagged with a tree, tag_chunk() checks whether there is > audit_tree_group mark attached to the inode and adds one if not. However > nothing protects another tag_chunk() to add the mark between we've > checked and try to add the fsnotify mark thus resulting in an error from > fsnotify_add_mark() and consequently an ENOSPC error from tag_chunk(). > > Fix the problem by holding mark_mutex over the whole check-insert code > sequence. > > Signed-off-by: Jan Kara <jack@xxxxxxx> > --- > kernel/audit_tree.c | 26 ++++++++++++++++---------- > 1 file changed, 16 insertions(+), 10 deletions(-) ... > diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c > index 1c82eb6674c4..de8d344d91b1 100644 > --- a/kernel/audit_tree.c > +++ b/kernel/audit_tree.c > @@ -342,25 +342,29 @@ static void untag_chunk(struct node *p) > spin_lock(&hash_lock); > } > > +/* Call with group->mark_mutex held, releases it */ Stuff like that always makes me nervous. Could we defer releasing the mutex to the caller, after create_chunk() returns? It looks like fsnotify_destroy_mark() allows a single level of nesting so it should be okay, yes? -- paul moore www.paul-moore.com
