[PATCH V2] namei: free new_dentry late

From: Pan Bian <bianpan2016@163.com>
To: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	Pan Bian <bianpan2016@163.com>
Subject: [PATCH V2] namei: free new_dentry late
Date: Sun, 25 Nov 2018 08:15:23 +0800	[thread overview]
Message-ID: <1543104923-81192-1-git-send-email-bianpan2016@163.com> (raw)

After calling dput(new_dentry), new_dentry is passed to fsnotify_move.
This may result in a use-after-free bug. This patch moves the put
operation late.

Fixes: da1ce0670c14("vfs: add cross-rename")
Signed-off-by: Pan Bian <bianpan2016@163.com>
---
V2: correct the fixes commit information
---
 fs/namei.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/namei.c b/fs/namei.c
index 0cab649..8b104d9 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4498,7 +4498,6 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 		unlock_two_nondirectories(source, target);
 	else if (target)
 		inode_unlock(target);
-	dput(new_dentry);
 	if (!error) {
 		fsnotify_move(old_dir, new_dir, old_name.name, is_dir,
 			      !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry);
@@ -4507,6 +4506,7 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 				      new_is_dir, NULL, new_dentry);
 		}
 	}
+	dput(new_dentry);
 	release_dentry_name_snapshot(&old_name);
 
 	return error;
-- 
2.7.4


