From: Jens Axboe <axboe@kernel.dk>
To: yinxin_1989 <yinxin_1989@aliyun.com>, viro <viro@zeniv.linux.org.uk>
Cc: linux-block <linux-block@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] io_uring: Fix NULL pointer dereference in io_sq_wq_submit_work()
Date: Tue, 1 Sep 2020 14:12:35 -0600 [thread overview]
Message-ID: <1925de10-3c07-0a0b-4434-1049b7ee52c3@kernel.dk> (raw)
In-Reply-To: <98f2cbbf-4f6f-501b-2f4e-1b8b803ce6a6@kernel.dk>
On 9/1/20 2:01 PM, Jens Axboe wrote:
> On 9/1/20 8:52 AM, Jens Axboe wrote:
>> On 8/31/20 10:59 PM, yinxin_1989 wrote:
>>>
>>>> On 8/31/20 7:54 PM, Xin Yin wrote:
>>>>> the commit <1c4404efcf2c0> ("<io_uring: make sure async workqueue
>>>>> is canceled on exit>") caused a crash in io_sq_wq_submit_work().
>>>>> when io_ring-wq get a req form async_list, which may not have been
>>>>> added to task_list. Then try to delete the req from task_list will caused
>>>>> a "NULL pointer dereference".
>>>>
>>>> Hmm, do you have a reproducer for this?
>>>
>>> I update code to linux5.4.y , and I can reproduce this issue on an arm
>>> board and my x86 pc by fio tools.
>>
>> Right, I figured this was 5.4 stable, as that's the only version that
>> has this patch.
>
> I took a closer look, and I think your patch can basically be boiled down
> to this single hunk. If you agree, can you resend your patch with the
> description based on that, then I'll get it queued up for 5.4-stable.
> Thanks!
Actually, we don't even need the irqsave, this should be enough:
diff --git a/fs/io_uring.c b/fs/io_uring.c
index fada14ee1cdc..2a539b794f3b 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2378,6 +2378,15 @@ static bool io_add_to_prev_work(struct async_list *list, struct io_kiocb *req)
list_del_init(&req->list);
ret = false;
}
+
+ if (ret) {
+ struct io_ring_ctx *ctx = req->ctx;
+
+ spin_lock_irq(&ctx->task_lock);
+ list_add(&req->task_list, &ctx->task_list);
+ req->work_task = NULL;
+ spin_unlock_irq(&ctx->task_lock);
+ }
spin_unlock(&list->lock);
return ret;
}
--
Jens Axboe
next prev parent reply other threads:[~2020-09-01 20:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200901015442.44831-1-yinxin_1989@aliyun.com>
2020-09-01 3:38 ` [PATCH] io_uring: Fix NULL pointer dereference in io_sq_wq_submit_work() Jens Axboe
[not found] ` <67f27d17-81fa-43a8-baa9-429b1ccd65d0.yinxin_1989@aliyun.com>
2020-09-01 14:52 ` Jens Axboe
2020-09-01 20:01 ` Jens Axboe
2020-09-01 20:12 ` Jens Axboe [this message]
[not found] <20200902015948.109580-1-yinxin_1989@aliyun.com>
2020-09-02 2:12 ` Jens Axboe
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