Re: [PATCH 04/22] fsnotify: Remove fsnotify_duplicate_mark()

On Thu, Dec 22, 2016 at 4:15 AM, Jan Kara <jack(a)suse.cz&gt; wrote: > There are only two calls sites of fsnotify_duplicate_mark(). Those are > in kernel/audit_tree.c and both are bogus. Vfsmount pointer is unused > for audit tree, inode pointer and group gets set in > fsnotify_add_mark_locked() later anyway, mask and free_mark are already > set in alloc_chunk(). In fact, calling fsnotify_duplicate_mark() is > actively harmful because following fsnotify_add_mark_locked() will leak > group reference by overwriting the group pointer. So just remove the two > calls to fsnotify_duplicate_mark() and the function. > > Signed-off-by: Jan Kara <jack(a)suse.cz&gt; > --- > fs/notify/mark.c | 12 ------------ > include/linux/fsnotify_backend.h | 2 -- > kernel/audit_tree.c | 6 ++---- > 3 files changed, 2 insertions(+), 18 deletions(-) At first glance this looks reasonable, although you keep mentioning "fsnotify_add_mark_locked" above when untag_chunk() is calling "fsnotify_add_mark"; I just wanted to make sure you hadn't intended to take the mutex in the audit code instead of relying on the locking in fsnotify_add_mark().

> diff --git a/fs/notify/mark.c b/fs/notify/mark.c > index d3fea0bd89e2..6043306e8e21 100644 > --- a/fs/notify/mark.c > +++ b/fs/notify/mark.c > @@ -510,18 +510,6 @@ void fsnotify_detach_group_marks(struct fsnotify_group *group) > } > } > > -void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old) > -{ > - assert_spin_locked(&old->lock); > - new->inode = old->inode; > - new->mnt = old->mnt; > - if (old->group) > - fsnotify_get_group(old->group); > - new->group = old->group; > - new->mask = old->mask; > - new->free_mark = old->free_mark; > -} > - > /* > * Nothing fancy, just initialize lists and locks and counters. > */ > diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h > index 0cf34d6cc253..487246546ebe 100644 > --- a/include/linux/fsnotify_backend.h > +++ b/include/linux/fsnotify_backend.h > @@ -323,8 +323,6 @@ extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(str > extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode); > /* find (and take a reference) to a mark associated with group and vfsmount */ > extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt); > -/* copy the values from old into new */ > -extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old); > /* set the ignored_mask of a mark */ > extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask); > /* set the mask of a mark (might pin the object into memory */ > diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c > index 8b1dde96a0fa..f3130eb0a4bd 100644 > --- a/kernel/audit_tree.c > +++ b/kernel/audit_tree.c > @@ -258,8 +258,7 @@ static void untag_chunk(struct node *p) > if (!new) > goto Fallback; > > - fsnotify_duplicate_mark(&new->mark, entry); > - if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.inode, NULL, 1)) { > + if (fsnotify_add_mark(&new->mark, entry->group, entry->inode, NULL, 1)) { > fsnotify_put_mark(&new->mark); > goto Fallback; > } > @@ -395,8 +394,7 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree) > return -ENOENT; > } > > - fsnotify_duplicate_mark(chunk_entry, old_entry); > - if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->inode, NULL, 1)) { > + if (fsnotify_add_mark(chunk_entry, old_entry->group, old_entry->inode, NULL, 1)) { > spin_unlock(&old_entry->lock); > fsnotify_put_mark(chunk_entry); > fsnotify_put_mark(old_entry); > -- > 2.10.2 > -- paul moore www.paul-moore.com