netdev - Re: [RFC PATCH v4 2/3] io_uring: add api to set / get napi configuration.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 22 Nov 2022 00:45:15 +0700
From:   Ammar Faizi <ammarfaizi2@...weeb.org>
To:     Stefan Roesch <shr@...kernel.io>,
        Facebook Kernel Team <kernel-team@...com>
Cc:     Jens Axboe <axboe@...nel.dk>,
        Olivier Langlois <olivier@...llion01.com>,
        netdev Mailing List <netdev@...r.kernel.org>,
        io-uring Mailing List <io-uring@...r.kernel.org>,
        Jakub Kicinski <kuba@...nel.org>
Subject: Re: [RFC PATCH v4 2/3] io_uring: add api to set / get napi
 configuration.

On 11/22/22 12:29 AM, Stefan Roesch wrote:
> +static int io_register_napi(struct io_ring_ctx *ctx, void __user *arg)
> +{
> +#ifdef CONFIG_NET_RX_BUSY_POLL
> +	const struct io_uring_napi curr = {
> +		.busy_poll_to = ctx->napi_busy_poll_to,
> +	};
> +	struct io_uring_napi *napi;
> +
> +	napi = memdup_user(arg, sizeof(*napi));
> +	if (IS_ERR(napi))
> +		return PTR_ERR(napi);
> +
> +	WRITE_ONCE(ctx->napi_busy_poll_to, napi->busy_poll_to);
> +
> +	kfree(napi);
> +
> +	if (copy_to_user(arg, &curr, sizeof(curr)))
> +		return -EFAULT;
> +
> +	return 0;

Considering:

    1) `struct io_uring_napi` is 16 bytes in size.

    2) The lifetime of `struct io_uring_napi *napi;` is brief.

There is no need to use memdup_user() and kfree(). You can place it
on the stack and use copy_from_user() instead.

-- 
Ammar Faizi