linux-ext4 - Re: [PATCH v3] ext4: truncate during setxattr leads to kernel panic

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: <20220405095451.kx43cdu2ureywgcq@riteshh-domain>
Date:   Tue, 5 Apr 2022 15:24:51 +0530
From:   Ritesh Harjani <ritesh.list@...il.com>
To:     anserper@...ru
Cc:     linux-ext4@...r.kernel.org,
        Andrew Perepechko <andrew.perepechko@....com>
Subject: Re: [PATCH v3] ext4: truncate during setxattr leads to kernel panic

On 22/04/02 11:40AM, anserper@...ru wrote:
> From: Andrew Perepechko <andrew.perepechko@....com>
>
> When changing a large xattr value to a different large xattr value,
> the old xattr inode is freed. Truncate during the final iput causes
> current transaction restart. Eventually, parent inode bh is marked
> dirty and kernel panic happens when jbd2 figures out that this bh
> belongs to the committed transaction.
>
> A possible fix is to call this final iput in a separate thread.
> This way, setxattr transactions will never be split into two.
> Since the setxattr code adds xattr inodes with nlink=0 into the
> orphan list, old xattr inodes will be properly cleaned up in
> any case.

Ok, I think there is a lot happening in above description. I think part of the
problem I am unable to understand it easily is because I haven't spend much time
with xattr code. But I think below 2 requests will be good to have -

1. Do we have the call stack for this problem handy. I think it will be good to
mention it in the commit message itself. It is sometimes easy to look at the
call stack if someone else encounters a similar problem. That also gives more
idea about where the problem is occuring.

2. Do we have a easy reproducer for this problem? I think it will be a good
   addition to fstests given that this adds another context in calling iput on
   old_ea_inode.

>
> Signed-off-by: Andrew Perepechko <andrew.perepechko@....com>
> HPE-bug-id: LUS-10534

^^^ I think above can be dropped. Any fixes tag instead?

-ritesh