linux-kernel - Re: [PATCH] ext4: Fix KASAN use-after-free in ext4_find

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: <19b5b9b3-5243-459b-a264-257f9c8324ec@huawei.com>
Date: Mon, 15 Dec 2025 09:54:27 +0800
From: Baokun Li <libaokun1@...wei.com>
To: 余昊铖 <3230100410@....edu.cn>
CC: <security@...nel.org>, <linux-ext4@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ext4: Fix KASAN use-after-free in ext4_find_extent

Hi,

On 2025-12-09 20:27, 余昊铖 wrote:
> Hello,
>
>
> I would like to report a potential security issue in the Linux kernel ext4 filesystem, which I found using a modified syzkaller-based kernel fuzzing tool that I developed.
>
I noticed that your configuration has CONFIG_BLK_DEV_WRITE_MOUNTED enabled.

This setting allows bare writes to an already mounted ext4 filesystem,
meaning certain ext4 metadata (like extent tree blocks) can be modified
without the filesystem being aware of the changes.

Could you please try disabling CONFIG_BLK_DEV_WRITE_MOUNTED and see
if the issue is still reproducible?

Cheers,
Baokun