linux-kernel - Re: [PATCH 4/8] pipe: fix limit checking in pipe_set

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

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/