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

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Date:   Thu, 29 Apr 2021 11:32:13 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Colin 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 11:26 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;

Colin, can you resend with the change?

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

-- 
Pavel Begunkov