From: Kees Cook <keescook@chromium.org>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Willy Tarreau <w@1wt.eu>,
Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.cz>, yalin wang <yalin.wang2010@gmail.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5] fs: clear file privilege bits when mmap writing
Date: Thu, 10 Dec 2015 14:00:07 -0800 [thread overview]
Message-ID: <CAGXu5jJWe8F-uj+ukPNMeo0W02YA4ssmLyBX4VTJ1nmeB-HxHw@mail.gmail.com> (raw)
In-Reply-To: <20151210215648.GG20997@ZenIV.linux.org.uk>
On Thu, Dec 10, 2015 at 1:56 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Thu, Dec 10, 2015 at 01:45:09PM -0800, Kees Cook wrote:
>> > but generally you need ->f_lock. And in situations where the bit can
>> > go only off->on, check it lockless, skip the whole thing entirely if it's
>> > already set and grab the spinlock otherwise.
>>
>> And I can take f_lock safely under mmap_sem?
>
> Are you asking whether it's safe to take a spinlock under an rwsem?
I keep getting various surprises while trying to implement this
change, so yeah, I just want to make sure I won't waste my time adding
taking the spinlock to the patch.
-Kees
--
Kees Cook
Chrome OS & Brillo Security
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prev parent reply other threads:[~2015-12-10 22:00 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-09 22:51 [PATCH v5] fs: clear file privilege bits when mmap writing Kees Cook
2015-12-10 1:21 ` Christoph Hellwig
2015-12-10 3:25 ` Kees Cook
2015-12-10 4:14 ` Al Viro
2015-12-10 7:06 ` Willy Tarreau
2015-12-10 7:10 ` Willy Tarreau
2015-12-10 18:05 ` Kees Cook
2015-12-10 18:16 ` Willy Tarreau
2015-12-10 18:18 ` Kees Cook
2015-12-10 19:33 ` Al Viro
2015-12-10 19:47 ` Kees Cook
2015-12-10 20:27 ` Al Viro
2015-12-10 21:45 ` Kees Cook
2015-12-10 21:56 ` Al Viro
2015-12-10 22:00 ` Kees Cook [this message]
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