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 <j...@suse.cz>
---
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 497395c8274b..99528618d382 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 3d286ff49ab0..99644e18544a 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 */
--
1.8.1.4
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