linux-kernel - [PATCH 21/67] cachefiles: Prevent inode from going away when burying a dentry

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 18 Oct 2021 15:56:01 +0100
From:   David Howells <dhowells@...hat.com>
To:     linux-cachefs@...hat.com
Cc:     dhowells@...hat.com, Trond Myklebust <trondmy@...merspace.com>,
        Anna Schumaker <anna.schumaker@...app.com>,
        Steve French <sfrench@...ba.org>,
        Dominique Martinet <asmadeus@...ewreck.org>,
        Jeff Layton <jlayton@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Omar Sandoval <osandov@...ndov.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-afs@...ts.infradead.org, linux-nfs@...r.kernel.org,
        linux-cifs@...r.kernel.org, ceph-devel@...r.kernel.org,
        v9fs-developer@...ts.sourceforge.net,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 21/67] cachefiles: Prevent inode from going away when burying
 a dentry

When deleting a file, we want to make sure that the inode doesn't get
detached from it (leading to ->d_inode being cleared) as we may still want
to touch the inode afterwards (we want to clear the belongs-to-kernel flag
and we may have the dentry referred to by a file struct).

Do this by getting an extra ref on the dentry around the vfs_unlink() call
so that d_delete() doesn't see the refcount == 1.

Signed-off-by: David Howells <dhowells@...hat.com>
---

 fs/cachefiles/namei.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index 4bd31be3be30..04c767624e3d 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -106,7 +106,9 @@ static int cachefiles_bury_object(struct cachefiles_cache *cache,
 			cachefiles_io_error(cache, "Unlink security error");
 		} else {
 			trace_cachefiles_unlink(object, rep, why);
+			dget(rep);
 			ret = vfs_unlink(&init_user_ns, d_inode(dir), rep, NULL);
+			dput(rep);
 		}
 
 		inode_unlock(d_inode(dir));