linux-ext4 - Re: [PATCH v8 16/19] fsnotify: generate pre-content permission event on page fault

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: <604c3501-f134-4a6e-ad41-ace84c2fd902@gmail.com>
Date: Mon, 9 Dec 2024 13:56:47 +0100
From: Klara Modin <klarasmodin@...il.com>
To: Jan Kara <jack@...e.cz>
Cc: Josef Bacik <josef@...icpanda.com>, kernel-team@...com,
 linux-fsdevel@...r.kernel.org, amir73il@...il.com, brauner@...nel.org,
 torvalds@...ux-foundation.org, viro@...iv.linux.org.uk,
 linux-xfs@...r.kernel.org, linux-btrfs@...r.kernel.org, linux-mm@...ck.org,
 linux-ext4@...r.kernel.org, sraithal@....com
Subject: Re: [PATCH v8 16/19] fsnotify: generate pre-content permission event
 on page fault

Hi,

On 2024-12-09 13:31, Jan Kara wrote:
> Hello!
> 
> On Sun 08-12-24 17:58:42, Klara Modin wrote:
>> On 2024-11-15 16:30, Josef Bacik wrote:
>>> FS_PRE_ACCESS or FS_PRE_MODIFY will be generated on page fault depending
>>> on the faulting method.
>>>
>>> This pre-content event is meant to be used by hierarchical storage
>>> managers that want to fill in the file content on first read access.
>>>
>>> Export a simple helper that file systems that have their own ->fault()
>>> will use, and have a more complicated helper to be do fancy things with
>>> in filemap_fault.
>>>
>>
>> This patch (0790303ec869d0fd658a548551972b51ced7390c in next-20241206)
>> interacts poorly with some programs which hang and are stuck at 100 % sys
>> cpu usage (examples of programs are logrotate and atop with root
>> privileges).
>>
>> I also retested the new version on Jan Kara's for_next branch and it behaves
>> the same way.
> 
> Thanks for report! What is your kernel config please? I've just fixed a
> bug reported by [1] which manifested in the same way with
> CONFIG_FANOTIFY_ACCESS_PERMISSIONS=n.
> 
> Can you perhaps test with my for_next branch I've just pushed out? Thanks!
> 
> 								Honza

My config was attached, but yes, I have 
CONFIG_FANOTIFY_ACCESS_PERMISSIONS=n. I tried the tip by Srikanth Aithal 
to enable it and that resolved the issue.

Your new for_next branch resolved the 
CONFIG_FANOTIFY_ACCESS_PERMISSIONS=n case for me.

Thanks,
Klara Modin