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authorAl Viro <viro@zeniv.linux.org.uk>2020-09-09 22:25:06 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-10-07 08:02:55 +0200
commitbdb43b31e65d418008a7f6718bbd2ca5ee04669a (patch)
tree1f787c003ae93f849f38ca18bd70dbbda3de440b
parent5e6bc9b1f1aef66fc4bae1a40afad33a8458e368 (diff)
epoll: do not insert into poll queues until all sanity checks are done
commit f8d4f44df056c5b504b0d49683fb7279218fd207 upstream. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/eventpoll.c37
1 files changed, 18 insertions, 19 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 8107e06d7f6f..5207dfc85b78 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1522,6 +1522,22 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
RCU_INIT_POINTER(epi->ws, NULL);
}
+ /* Add the current item to the list of active epoll hook for this file */
+ spin_lock(&tfile->f_lock);
+ list_add_tail_rcu(&epi->fllink, &tfile->f_ep_links);
+ spin_unlock(&tfile->f_lock);
+
+ /*
+ * Add the current item to the RB tree. All RB tree operations are
+ * protected by "mtx", and ep_insert() is called with "mtx" held.
+ */
+ ep_rbtree_insert(ep, epi);
+
+ /* now check if we've created too many backpaths */
+ error = -EINVAL;
+ if (full_check && reverse_path_check())
+ goto error_remove_epi;
+
/* Initialize the poll table using the queue callback */
epq.epi = epi;
init_poll_funcptr(&epq.pt, ep_ptable_queue_proc);
@@ -1544,22 +1560,6 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
if (epi->nwait < 0)
goto error_unregister;
- /* Add the current item to the list of active epoll hook for this file */
- spin_lock(&tfile->f_lock);
- list_add_tail_rcu(&epi->fllink, &tfile->f_ep_links);
- spin_unlock(&tfile->f_lock);
-
- /*
- * Add the current item to the RB tree. All RB tree operations are
- * protected by "mtx", and ep_insert() is called with "mtx" held.
- */
- ep_rbtree_insert(ep, epi);
-
- /* now check if we've created too many backpaths */
- error = -EINVAL;
- if (full_check && reverse_path_check())
- goto error_remove_epi;
-
/* We have to drop the new item inside our item list to keep track of it */
write_lock_irq(&ep->lock);
@@ -1588,6 +1588,8 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
return 0;
+error_unregister:
+ ep_unregister_pollwait(ep, epi);
error_remove_epi:
spin_lock(&tfile->f_lock);
list_del_rcu(&epi->fllink);
@@ -1595,9 +1597,6 @@ error_remove_epi:
rb_erase_cached(&epi->rbn, &ep->rbr);
-error_unregister:
- ep_unregister_pollwait(ep, epi);
-
/*
* We need to do this because an event could have been arrived on some
* allocated wait queue. Note that we don't care about the ep->ovflist