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From: Kees Cook <keescook@chromium.org>
To: Eric Biggers <ebiggers3@gmail.com>
Cc: "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	Willy Tarreau <w@1wt.eu>, Mikulas Patocka <mpatocka@redhat.com>,
	"Luis R . Rodriguez" <mcgrof@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Eric Biggers <ebiggers@google.com>
Subject: Re: [PATCH 1/7] pipe, sysctl: drop 'min' parameter from pipe-max-size converter
Date: Wed, 10 Jan 2018 09:30:13 -0800	[thread overview]
Message-ID: <CAGXu5jJt+gv=CKv_2Dekf2RxiY_=sdz8OCpxzouP3CFNeGT6+Q@mail.gmail.com> (raw)
In-Reply-To: <20180110022954.GA931@zzz.localdomain>

On Tue, Jan 9, 2018 at 6:29 PM, Eric Biggers <ebiggers3@gmail.com> wrote:
> On Tue, Jan 09, 2018 at 02:20:45PM -0800, Kees Cook wrote:
>> On Sun, Jan 7, 2018 at 9:35 PM, Eric Biggers <ebiggers3@gmail.com> wrote:
>> > From: Eric Biggers <ebiggers@google.com>
>> >
>> > Before validating the given value against pipe_min_size,
>> > do_proc_dopipe_max_size_conv() calls round_pipe_size(), which rounds the
>> > value up to pipe_min_size.  Therefore, the second check against
>> > pipe_min_size is redundant.  Remove it.
>>
>> Well, it's not redundant: it provides a hint to anyone trying to tweak
>> the sysctl about the minimum value. I think this should stay, but that
>> pipe_min_size should be made const.
>>
>> -Kees
>>
>
> It *is* redundant, because it doesn't do anything.  round_pipe_size() already
> rounds the value up to the minimum.

Ah, yes, I see it now. Wow are the sysctl functions convoluted here!

Acked-by: Kees Cook <keescook@chromium.org>

-Kees

-- 
Kees Cook
Pixel Security

  reply	other threads:[~2018-01-10 17:30 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-08  5:35 [PATCH 0/7] pipe: buffer limits fixes and cleanups Eric Biggers
2018-01-08  5:35 ` [PATCH 1/7] pipe, sysctl: drop 'min' parameter from pipe-max-size converter Eric Biggers
2018-01-09 22:20   ` Kees Cook
2018-01-10  2:29     ` Eric Biggers
2018-01-10 17:30       ` Kees Cook [this message]
2018-01-08  5:35 ` [PATCH 2/7] pipe, sysctl: remove pipe_proc_fn() Eric Biggers
2018-01-08  5:35 ` [PATCH 3/7] pipe: actually allow root to exceed the pipe buffer limits Eric Biggers
2018-01-09 22:23   ` Kees Cook
2018-01-10  2:34     ` Eric Biggers
2018-01-08  5:35 ` [PATCH 4/7] pipe: fix off-by-one error when checking " Eric Biggers
2018-01-08  6:42   ` Willy Tarreau
2018-01-08  5:35 ` [PATCH 5/7] pipe: reject F_SETPIPE_SZ with size over UINT_MAX Eric Biggers
2018-01-09 22:24   ` Kees Cook
2018-01-08  5:35 ` [PATCH 6/7] pipe: simplify round_pipe_size() Eric Biggers
2018-01-09 22:27   ` Kees Cook
2018-01-10  2:52     ` Eric Biggers
2018-01-10  3:13       ` Kees Cook
2018-01-08  5:35 ` [PATCH 7/7] pipe: read buffer limits atomically Eric Biggers
2018-01-09 22:27   ` Kees Cook

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