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| author | Miklos Szeredi <mszeredi@redhat.com> | 2017-10-30 23:14:56 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-11-30 11:40:45 +0300 |
| commit | 1dd7dd07e875428e5f05ec55d90472ed6089b08e (patch) | |
| tree | b07a3a43bf07097b502ee922928675a14d015c25 /fs/notify | |
| parent | 5c21c3dde403cdf4b9c777e9dbd9399e6eb8e9b6 (diff) | |
| download | linux-1dd7dd07e875428e5f05ec55d90472ed6089b08e.tar.xz | |
fanotify: fix fsnotify_prepare_user_wait() failure
commit f37650f1c7c71cf5180b43229d13b421d81e7170 upstream.
If fsnotify_prepare_user_wait() fails, we leave the event on the
notification list. Which will result in a warning in
fsnotify_destroy_event() and later use-after-free.
Instead of adding a new helper to remove the event from the list in this
case, I opted to move the prepare/finish up into fanotify_handle_event().
This will allow these to be moved further out into the generic code later,
and perhaps let us move to non-sleeping RCU.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 05f0e38724e8 ("fanotify: Release SRCU lock when waiting for userspace response")
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/notify')
| -rw-r--r-- | fs/notify/fanotify/fanotify.c | 33 |
1 files changed, 20 insertions, 13 deletions
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index 09640b546363..3c7053207297 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -65,19 +65,8 @@ static int fanotify_get_response(struct fsnotify_group *group, pr_debug("%s: group=%p event=%p\n", __func__, group, event); - /* - * fsnotify_prepare_user_wait() fails if we race with mark deletion. - * Just let the operation pass in that case. - */ - if (!fsnotify_prepare_user_wait(iter_info)) { - event->response = FAN_ALLOW; - goto out; - } - wait_event(group->fanotify_data.access_waitq, event->response); - fsnotify_finish_user_wait(iter_info); -out: /* userspace responded, convert to something usable */ switch (event->response) { case FAN_ALLOW: @@ -212,9 +201,21 @@ static int fanotify_handle_event(struct fsnotify_group *group, pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode, mask); +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + if (mask & FAN_ALL_PERM_EVENTS) { + /* + * fsnotify_prepare_user_wait() fails if we race with mark + * deletion. Just let the operation pass in that case. + */ + if (!fsnotify_prepare_user_wait(iter_info)) + return 0; + } +#endif + event = fanotify_alloc_event(inode, mask, data); + ret = -ENOMEM; if (unlikely(!event)) - return -ENOMEM; + goto finish; fsn_event = &event->fse; ret = fsnotify_add_event(group, fsn_event, fanotify_merge); @@ -224,7 +225,8 @@ static int fanotify_handle_event(struct fsnotify_group *group, /* Our event wasn't used in the end. Free it. */ fsnotify_destroy_event(group, fsn_event); - return 0; + ret = 0; + goto finish; } #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS @@ -233,6 +235,11 @@ static int fanotify_handle_event(struct fsnotify_group *group, iter_info); fsnotify_destroy_event(group, fsn_event); } +finish: + if (mask & FAN_ALL_PERM_EVENTS) + fsnotify_finish_user_wait(iter_info); +#else +finish: #endif return ret; } |