linux-kernel - Re: [PATCH] io_uring: Don't set affinity on a dying sqpoll thread

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Date:   Tue, 29 Aug 2023 11:37:08 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     syzbot <syzbot+c74fea926a78b8a91042@...kaller.appspotmail.com>,
        Gabriel Krisman Bertazi <krisman@...e.de>
Cc:     asml.silence@...il.com, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH] io_uring: Don't set affinity on a dying sqpoll thread


On Mon, 28 Aug 2023 19:42:49 -0400, Gabriel Krisman Bertazi wrote:
> Syzbot reported a null-ptr-deref of sqd->thread inside
> io_sqpoll_wq_cpu_affinity.  It turns out the sqd->thread can go away
> from under us during io_uring_register, in case the process gets a
> fatal signal during io_uring_register.
> 
> It is not particularly hard to hit the race, and while I am not sure
> this is the exact case hit by syzbot, it solves it.  Finally, checking
> ->thread is enough to close the race because we locked sqd while
> "parking" the thread, thus preventing it from going away.
> 
> [...]

Applied, thanks!

[1/1] io_uring: Don't set affinity on a dying sqpoll thread
      commit: 37b1499057f61de370dbd8f0c296274ab7186605

Best regards,
-- 
Jens Axboe