From: Al Viro <viro@zeniv.linux.org.uk>
Date: Thu, 24 Sep 2020 23:41:58 +0000 (-0400)
Subject: ep_create_wakeup_source(): dentry name can change under you...
X-Git-Tag: v4.14.201~42
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=a3915080e95da5257c541bbc39fa4007076d8fa3;p=users%2Fdwmw2%2Flinux.git

ep_create_wakeup_source(): dentry name can change under you...

commit 3701cb59d892b88d569427586f01491552f377b1 upstream.

or get freed, for that matter, if it's a long (separately stored)
name.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 634baff806945..c9feb119aa473 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1389,7 +1389,7 @@ static int reverse_path_check(void)
 
 static int ep_create_wakeup_source(struct epitem *epi)
 {
-	const char *name;
+	struct name_snapshot n;
 	struct wakeup_source *ws;
 
 	if (!epi->ep->ws) {
@@ -1398,8 +1398,9 @@ static int ep_create_wakeup_source(struct epitem *epi)
 			return -ENOMEM;
 	}
 
-	name = epi->ffd.file->f_path.dentry->d_name.name;
-	ws = wakeup_source_register(name);
+	take_dentry_name_snapshot(&n, epi->ffd.file->f_path.dentry);
+	ws = wakeup_source_register(n.name);
+	release_dentry_name_snapshot(&n);
 
 	if (!ws)
 		return -ENOMEM;