linux-kernel - Re: [PATCH 5.6] io_uring: NULL-deref for IOSQE

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Message-ID: <6ebc5e8a-7a6c-2537-9050-fe4e5c4f014d@gmail.com>
Date:   Sat, 14 Mar 2020 00:29:28 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5.6] io_uring: NULL-deref for IOSQE_{ASYNC,DRAIN}

On 13/03/2020 23:28, Pavel Begunkov wrote:
> Hmm, found unreliably failing the across-fork test. I don't know whether it's
> this patch specific, but need to take a look there first.

It's good to go, just used outdated tests.
The reproducer is attached.

> 
>>
>> Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
>> ---
>>  fs/io_uring.c | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index 55afae6f0cf4..9d43efbec960 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -4813,6 +4813,9 @@ static int io_req_defer_prep(struct io_kiocb *req,
>>  {
>>  	ssize_t ret = 0;
>>  
>> +	if (!sqe)
>> +		return 0;
>> +
>>  	if (io_op_defs[req->opcode].file_table) {
>>  		ret = io_grab_files(req);
>>  		if (unlikely(ret))
>> @@ -5655,6 +5658,11 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
>>  		if (sqe_flags & (IOSQE_IO_LINK|IOSQE_IO_HARDLINK)) {
>>  			req->flags |= REQ_F_LINK;
>>  			INIT_LIST_HEAD(&req->link_list);
>> +
>> +			if (io_alloc_async_ctx(req)) {
>> +				ret = -EAGAIN;
>> +				goto err_req;
>> +			}
>>  			ret = io_req_defer_prep(req, sqe);
>>  			if (ret)
>>  				req->flags |= REQ_F_FAIL_LINK;
>>
> 

-- 
Pavel Begunkov

View attachment "read-write2.c" of type "text/x-csrc" (2476 bytes)