[PATCH 4.19 37/38] ep_create_wakeup_source(): dentry name can change under you...

[Greg Kroah-Hartman]

From: Al Viro <v...@zeniv.linux.org.uk>

commit 3701cb59d892b88d569427586f01491552f377b1 upstream.

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

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

---
 fs/eventpoll.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1376,7 +1376,7 @@ 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) {
@@ -1385,8 +1385,9 @@ static int ep_create_wakeup_source(struc
                        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;