linux-kernel - Re: [PATCH][next] io_uring: Fix memory leak on error return path.

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Date:   Thu, 29 Apr 2021 11:41:26 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Colin Ian King <colin.king@...onical.com>,
        Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] io_uring: Fix memory leak on error return path.

On 4/29/21 11:36 AM, Colin Ian King wrote:
> On 29/04/2021 11:32, Pavel Begunkov wrote:
>> On 4/29/21 11:26 AM, Colin King wrote:
>>> From: Colin Ian King <colin.king@...onical.com>
>>>
>>> Currently the -EINVAL error return path is leaking memory allocated
>>> to data. Fix this by kfree'ing data before the return.
>>>
>>> Addresses-Coverity: ("Resource leak")
>>> Fixes: c3a40789f6ba ("io_uring: allow empty slots for reg buffers")
>>> Signed-off-by: Colin Ian King <colin.king@...onical.com>
>>> ---
>>>  fs/io_uring.c | 4 +++-
>>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>>> index 47c2f126f885..beeb477e4f6a 100644
>>> --- a/fs/io_uring.c
>>> +++ b/fs/io_uring.c
>>> @@ -8417,8 +8417,10 @@ static int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
>>>  		ret = io_buffer_validate(&iov);
>>>  		if (ret)
>>>  			break;
>>> -		if (!iov.iov_base && tag)
>>> +		if (!iov.iov_base && tag) {> +			kfree(data);
>>>  			return -EINVAL;
>>> +		}
>>
>> Buggy indeed, should have been:
>>
>> ret = -EINVAL;
>> break;
> Ah, thanks.
> 
>>
>> Colin, can you resend with the change?
> 
> Will do in a moment or so.

Hmm, there are actually two of them, look for

"iov.iov_base && tag"

>>
>>>  
>>>  		ret = io_sqe_buffer_register(ctx, &iov, &ctx->user_bufs[i],
>>>  					     &last_hpage);
>>>
>>
> 

-- 
Pavel Begunkov