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author | Jan Kara <jack@suse.cz> | 2014-01-28 18:53:22 +0100 |
---|---|---|
committer | Jan Kara <jack@suse.cz> | 2014-01-29 13:57:10 +0100 |
commit | 83c0e1b442b488571f4fef4a91c2fe52eed6c705 (patch) | |
tree | b29a85223f2e5e166f075266edb1bf2e0ef5cf57 /fs | |
parent | 13116dfd13c8c9d60ea04ece13419af2de8e2e37 (diff) | |
download | lwn-83c0e1b442b488571f4fef4a91c2fe52eed6c705.tar.gz lwn-83c0e1b442b488571f4fef4a91c2fe52eed6c705.zip |
fsnotify: Do not return merged event from fsnotify_add_notify_event()
The event returned from fsnotify_add_notify_event() cannot ever be used
safely as the event may be freed by the time the function returns (after
dropping notification_mutex). So change the prototype to just return
whether the event was added or merged into some existing event.
Reported-and-tested-by: Jiri Kosina <jkosina@suse.cz>
Reported-and-tested-by: Dave Jones <davej@fedoraproject.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/notify/fanotify/fanotify.c | 18 | ||||
-rw-r--r-- | fs/notify/inotify/inotify_fsnotify.c | 19 | ||||
-rw-r--r-- | fs/notify/notification.c | 24 |
3 files changed, 26 insertions, 35 deletions
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index cc78e2fbc8e4..c7e5e8f54748 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -28,8 +28,7 @@ static bool should_merge(struct fsnotify_event *old_fsn, } /* and the list better be locked by something too! */ -static struct fsnotify_event *fanotify_merge(struct list_head *list, - struct fsnotify_event *event) +static int fanotify_merge(struct list_head *list, struct fsnotify_event *event) { struct fsnotify_event *test_event; bool do_merge = false; @@ -43,7 +42,7 @@ static struct fsnotify_event *fanotify_merge(struct list_head *list, * one we should check for permission response. */ if (event->mask & FAN_ALL_PERM_EVENTS) - return NULL; + return 0; #endif list_for_each_entry_reverse(test_event, list, list) { @@ -54,10 +53,10 @@ static struct fsnotify_event *fanotify_merge(struct list_head *list, } if (!do_merge) - return NULL; + return 0; test_event->mask |= event->mask; - return test_event; + return 1; } #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS @@ -153,7 +152,6 @@ static int fanotify_handle_event(struct fsnotify_group *group, int ret = 0; struct fanotify_event_info *event; struct fsnotify_event *fsn_event; - struct fsnotify_event *notify_fsn_event; BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS); BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY); @@ -192,13 +190,11 @@ static int fanotify_handle_event(struct fsnotify_group *group, event->response = 0; #endif - notify_fsn_event = fsnotify_add_notify_event(group, fsn_event, - fanotify_merge); - if (notify_fsn_event) { + ret = fsnotify_add_notify_event(group, fsn_event, fanotify_merge); + if (ret) { /* Our event wasn't used in the end. Free it. */ fsnotify_destroy_event(group, fsn_event); - if (IS_ERR(notify_fsn_event)) - return PTR_ERR(notify_fsn_event); + ret = 0; } #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c index aad1a35e9af1..d5ee56348bb8 100644 --- a/fs/notify/inotify/inotify_fsnotify.c +++ b/fs/notify/inotify/inotify_fsnotify.c @@ -53,15 +53,13 @@ static bool event_compare(struct fsnotify_event *old_fsn, return false; } -static struct fsnotify_event *inotify_merge(struct list_head *list, - struct fsnotify_event *event) +static int inotify_merge(struct list_head *list, + struct fsnotify_event *event) { struct fsnotify_event *last_event; last_event = list_entry(list->prev, struct fsnotify_event, list); - if (!event_compare(last_event, event)) - return NULL; - return last_event; + return event_compare(last_event, event); } int inotify_handle_event(struct fsnotify_group *group, @@ -73,9 +71,8 @@ int inotify_handle_event(struct fsnotify_group *group, { struct inotify_inode_mark *i_mark; struct inotify_event_info *event; - struct fsnotify_event *added_event; struct fsnotify_event *fsn_event; - int ret = 0; + int ret; int len = 0; int alloc_len = sizeof(struct inotify_event_info); @@ -110,18 +107,16 @@ int inotify_handle_event(struct fsnotify_group *group, if (len) strcpy(event->name, file_name); - added_event = fsnotify_add_notify_event(group, fsn_event, inotify_merge); - if (added_event) { + ret = fsnotify_add_notify_event(group, fsn_event, inotify_merge); + if (ret) { /* Our event wasn't used in the end. Free it. */ fsnotify_destroy_event(group, fsn_event); - if (IS_ERR(added_event)) - ret = PTR_ERR(added_event); } if (inode_mark->mask & IN_ONESHOT) fsnotify_destroy_mark(inode_mark, group); - return ret; + return 0; } static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group) diff --git a/fs/notify/notification.c b/fs/notify/notification.c index 952237b8e2d2..18b3c4427dca 100644 --- a/fs/notify/notification.c +++ b/fs/notify/notification.c @@ -79,15 +79,15 @@ void fsnotify_destroy_event(struct fsnotify_group *group, /* * Add an event to the group notification queue. The group can later pull this - * event off the queue to deal with. If the event is successfully added to the - * group's notification queue, a reference is taken on event. + * event off the queue to deal with. The function returns 0 if the event was + * added to the queue, 1 if the event was merged with some other queued event. */ -struct fsnotify_event *fsnotify_add_notify_event(struct fsnotify_group *group, - struct fsnotify_event *event, - struct fsnotify_event *(*merge)(struct list_head *, - struct fsnotify_event *)) +int fsnotify_add_notify_event(struct fsnotify_group *group, + struct fsnotify_event *event, + int (*merge)(struct list_head *, + struct fsnotify_event *)) { - struct fsnotify_event *return_event = NULL; + int ret = 0; struct list_head *list = &group->notification_list; pr_debug("%s: group=%p event=%p\n", __func__, group, event); @@ -98,14 +98,14 @@ struct fsnotify_event *fsnotify_add_notify_event(struct fsnotify_group *group, /* Queue overflow event only if it isn't already queued */ if (list_empty(&group->overflow_event.list)) event = &group->overflow_event; - return_event = event; + ret = 1; } if (!list_empty(list) && merge) { - return_event = merge(list, event); - if (return_event) { + ret = merge(list, event); + if (ret) { mutex_unlock(&group->notification_mutex); - return return_event; + return ret; } } @@ -115,7 +115,7 @@ struct fsnotify_event *fsnotify_add_notify_event(struct fsnotify_group *group, wake_up(&group->notification_waitq); kill_fasync(&group->fsn_fa, SIGIO, POLL_IN); - return return_event; + return ret; } /* |