From ff57cd5863cf3014c1c5ed62ce2715294f065b17 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Fri, 21 Feb 2014 19:14:11 +0100 Subject: [PATCH] fsnotify: Allocate overflow events with proper type Commit 7053aee26a35 "fsnotify: do not share events between notification groups" used overflow event statically allocated in a group with the size of the generic notification event. This causes problems because some code looks at type specific parts of event structure and gets confused by a random data it sees there and causes crashes. Fix the problem by allocating overflow event with type corresponding to the group type so code cannot get confused. Signed-off-by: Jan Kara --- fs/notify/fanotify/fanotify_user.c | 13 +++++++++++++ fs/notify/group.c | 8 +++++++- fs/notify/inotify/inotify_user.c | 12 ++++++++++++ fs/notify/notification.c | 4 ++-- include/linux/fsnotify_backend.h | 2 +- 5 files changed, 35 insertions(+), 4 deletions(-) diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index b6175fa11bf8..287a22c04149 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -698,6 +698,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) struct fsnotify_group *group; int f_flags, fd; struct user_struct *user; + struct fanotify_event_info *oevent; pr_debug("%s: flags=%d event_f_flags=%d\n", __func__, flags, event_f_flags); @@ -730,8 +731,20 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) group->fanotify_data.user = user; atomic_inc(&user->fanotify_listeners); + oevent = kmem_cache_alloc(fanotify_event_cachep, GFP_KERNEL); + if (unlikely(!oevent)) { + fd = -ENOMEM; + goto out_destroy_group; + } + group->overflow_event = &oevent->fse; + fsnotify_init_event(group->overflow_event, NULL, FS_Q_OVERFLOW); + oevent->tgid = get_pid(task_tgid(current)); + oevent->path.mnt = NULL; + oevent->path.dentry = NULL; + group->fanotify_data.f_flags = event_f_flags; #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + oevent->response = 0; mutex_init(&group->fanotify_data.access_mutex); init_waitqueue_head(&group->fanotify_data.access_waitq); INIT_LIST_HEAD(&group->fanotify_data.access_list); diff --git a/fs/notify/group.c b/fs/notify/group.c index ee674fe2cec7..ad1995980456 100644 --- a/fs/notify/group.c +++ b/fs/notify/group.c @@ -55,6 +55,13 @@ void fsnotify_destroy_group(struct fsnotify_group *group) /* clear the notification queue of all events */ fsnotify_flush_notify(group); + /* + * Destroy overflow event (we cannot use fsnotify_destroy_event() as + * that deliberately ignores overflow events. + */ + if (group->overflow_event) + group->ops->free_event(group->overflow_event); + fsnotify_put_group(group); } @@ -99,7 +106,6 @@ struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops) INIT_LIST_HEAD(&group->marks_list); group->ops = ops; - fsnotify_init_event(&group->overflow_event, NULL, FS_Q_OVERFLOW); return group; } diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c index 6528b5a54ca0..78a2ca3966c3 100644 --- a/fs/notify/inotify/inotify_user.c +++ b/fs/notify/inotify/inotify_user.c @@ -633,11 +633,23 @@ static int inotify_update_watch(struct fsnotify_group *group, struct inode *inod static struct fsnotify_group *inotify_new_group(unsigned int max_events) { struct fsnotify_group *group; + struct inotify_event_info *oevent; group = fsnotify_alloc_group(&inotify_fsnotify_ops); if (IS_ERR(group)) return group; + oevent = kmalloc(sizeof(struct inotify_event_info), GFP_KERNEL); + if (unlikely(!oevent)) { + fsnotify_destroy_group(group); + return ERR_PTR(-ENOMEM); + } + group->overflow_event = &oevent->fse; + fsnotify_init_event(group->overflow_event, NULL, FS_Q_OVERFLOW); + oevent->wd = -1; + oevent->sync_cookie = 0; + oevent->name_len = 0; + group->max_events = max_events; spin_lock_init(&group->inotify_data.idr_lock); diff --git a/fs/notify/notification.c b/fs/notify/notification.c index 6a4ba17c0395..1e58402171a5 100644 --- a/fs/notify/notification.c +++ b/fs/notify/notification.c @@ -98,11 +98,11 @@ int fsnotify_add_notify_event(struct fsnotify_group *group, if (group->q_len >= group->max_events) { ret = 2; /* Queue overflow event only if it isn't already queued */ - if (!list_empty(&group->overflow_event.list)) { + if (!list_empty(&group->overflow_event->list)) { mutex_unlock(&group->notification_mutex); return ret; } - event = &group->overflow_event; + event = group->overflow_event; goto queue; } diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h index c84bc7c2bfc8..64cf3ef50696 100644 --- a/include/linux/fsnotify_backend.h +++ b/include/linux/fsnotify_backend.h @@ -160,7 +160,7 @@ struct fsnotify_group { struct fasync_struct *fsn_fa; /* async notification */ - struct fsnotify_event overflow_event; /* Event we queue when the + struct fsnotify_event *overflow_event; /* Event we queue when the * notification list is too * full */