linux-kernel - Re: [PATCH v2] audit: Avoid excessive dput/dget in audit

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <8a456257-6f7e-4d0a-b38d-3c2aefee76bb@redhat.com>
Date: Thu, 5 Feb 2026 20:20:19 -0500
From: Waiman Long <llong@...hat.com>
To: Al Viro <viro@...iv.linux.org.uk>, Waiman Long <llong@...hat.com>
Cc: Paul Moore <paul@...l-moore.com>, Eric Paris <eparis@...hat.com>,
 Christian Brauner <brauner@...nel.org>, linux-kernel@...r.kernel.org,
 audit@...r.kernel.org, Richard Guy Briggs <rgb@...hat.com>,
 Ricardo Robaina <rrobaina@...hat.com>
Subject: Re: [PATCH v2] audit: Avoid excessive dput/dget in audit_context
 setup and reset paths

On 2/5/26 6:53 PM, Al Viro wrote:
> On Wed, Feb 04, 2026 at 11:45:17PM -0500, Waiman Long wrote:
>
>> @@ -70,6 +74,8 @@ void chroot_fs_refs(const struct path *old_root, const
>> struct>
>>                                  count++;
>>                                  path_get(new_root);
>>                          }
>> +                       count += fs->pwd_xrefs;
>> +                       fs->pwd_xrefs = 0;
>>                          write_sequnlock(&fs->seq);
> Nope - you only need that for threads that have ->pwd equal to old_root.
> Incidentally, I'd forgotten about that sucker - it kills the idea of
> fdget-like tricks dead, more's the pity.  Third-party modification of
> task->fs->pwd (under task->lock and task->fs->seq), possible even with
> task->fs->users == 1.

Yes, I am aware of that when I took a further look at the patch that I 
sent out yesterday. I am testing the updated patch now and is trying to 
figure out why I get a warning from mntput_no_expire_slowpath() with a 
count of -1 when doing an umount. It is off by 1 somewhere. I will post 
the patch once I resolve this bug.

Thanks,
Longman