Re: [PATCH 4/8] pipe: fix limit checking in pipe_set_size() - Michael Kerrisk (man-pages)

From: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
To: Willy Tarreau <w@1wt.eu>
Cc: mtk.manpages@gmail.com, Andrew Morton <akpm@linux-foundation.org>,
	Vegard Nossum <vegard.nossum@oracle.com>,
	socketpair@gmail.com,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	Jens Axboe <axboe@fb.com>, Al Viro <viro@zeniv.linux.org.uk>,
	linux-api@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/8] pipe: fix limit checking in pipe_set_size()
Date: Sat, 20 Aug 2016 08:51:26 +1200	[thread overview]
Message-ID: <dc392fd9-f848-8ad4-13b2-549fc1a57516@gmail.com> (raw)
In-Reply-To: <20160819054818.GH17944@1wt.eu>

On 08/19/2016 05:48 PM, Willy Tarreau wrote:
> Hi Michael,
> 
> Since you're changing this code, it's probably worth swapping the size
> check and capable() below to save a function call in the normal path :
> 
> On Fri, Aug 19, 2016 at 05:25:35PM +1200, Michael Kerrisk (man-pages) wrote:
>> +	if (nr_pages > pipe->buffers) {
>> +		if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {
> 
> =>		if (size > pipe_max_size && !capable(CAP_SYS_RESOURCE)) {
> 
>> +			ret = -EPERM;
>> +			goto out_revert_acct;
>> +		} else if ((too_many_pipe_buffers_hard(pipe->user) ||
>> +				too_many_pipe_buffers_soft(pipe->user)) &&
>> +				!capable(CAP_SYS_RESOURCE) &&
>> +				!capable(CAP_SYS_ADMIN)) {
>> +			ret = -EPERM;
>> +			goto out_revert_acct;
>> +		}
>> +	}
> (...)

Thanks, Willy. Fixed for the next iteration. (And I made the same fix made 
also in the 8/8 patch).

Cheers,

Michael

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/