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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 6/7] pipe: simplify round_pipe_size()
Date: Tue, 9 Jan 2018 19:13:34 -0800 [thread overview]
Message-ID: <CAGXu5jJ61T_t-Out9OZQeVC0KB5PQ+Kik-6eynTXE0nBCFYimw@mail.gmail.com> (raw)
In-Reply-To: <20180110025201.GC931@zzz.localdomain>
On Tue, Jan 9, 2018 at 6:52 PM, Eric Biggers <ebiggers3@gmail.com> wrote:
> On Tue, Jan 09, 2018 at 02:27:10PM -0800, Kees Cook wrote:
>>
>> > @@ -1054,9 +1048,6 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg)
>> > return -EINVAL;
>> > nr_pages = size >> PAGE_SHIFT;
>> >
>> > - if (!nr_pages)
>> > - return -EINVAL;
>> > -
>>
>> I would just leave this hunk anyway: it's defensive for any future
>> changes. Maybe add a comment describing why it's currently redundant?
>>
>
> I don't know; I find it really confusing to have two slightly different checks
> for the same thing, as it implies that they actually need to be there for a
> reason. How about just checking nr_pages?
>
> size = round_pipe_size(arg);
> nr_pages = size >> PAGE_SHIFT;
>
> if (nr_pages == 0)
> return -EINVAL;
Oh yeah! I like that.
-Kees
--
Kees Cook
Pixel Security
next prev parent reply other threads:[~2018-01-10 3:13 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
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 [this message]
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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