linux-kernel - Re: [syzbot] [io-uring?] INFO: task hung in io_uring_del_tctx

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: <e6fd5269-d6c0-4925-912a-7967313d991c@kernel.dk>
Date: Mon, 27 Oct 2025 17:15:56 -0600
From: Jens Axboe <axboe@...nel.dk>
To: Keith Busch <kbusch@...nel.org>
Cc: syzbot <syzbot+10a9b495f54a17b607a6@...kaller.appspotmail.com>,
 io-uring@...r.kernel.org, linux-kernel@...r.kernel.org,
 syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [io-uring?] INFO: task hung in io_uring_del_tctx_node
 (5)

On 10/27/25 4:57 PM, Keith Busch wrote:
> On Mon, Oct 27, 2025 at 04:04:05PM -0600, Jens Axboe wrote:
>>
>> commit 1cba30bf9fdd6c982708f3587f609a30c370d889
>> Author: Keith Busch <kbusch@...nel.org>
>> Date:   Thu Oct 16 11:09:38 2025 -0700
>>
>>     io_uring: add support for IORING_SETUP_SQE_MIXED
>>
>> leaves fdinfo open up to being broken. Before, we had:
>>
>> sq_entries = min(sq_tail - sq_head, ctx->sq_entries);
>>
>> as a cap for the loop, now you just have:
>>
>> while (sq_head < sq_tail) {
>>
>> which seems like a bad idea. It's also missing an sq_head increment if
>> we hit this condition:
> 
> This would have to mean the application did an invalid head ring-wrap,
> right?

Right, it's a malicious use case. But you always have to be able to deal
with those, it's not like broken hardware in that sense.

> Regardless, I messed up and the wrong thing will happen here in
> that case as well as the one you mentioned.

Yep I think so too, was more interested in your opinion on the patch :-)

-- 
Jens Axboe