linux-kernel - RE: [PATCH] libnvdimm/pmem: Bypass CONFIG_HARDENED

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Message-ID: <ac76e29576b14fcb9a18e5a9e6ab8394@AcuMS.aculab.com>
Date:   Fri, 17 May 2019 16:14:03 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Kees Cook' <keescook@...omium.org>
CC:     'Jan Kara' <jack@...e.cz>, Dan Williams <dan.j.williams@...el.com>,
        "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Jeff Moyer <jmoyer@...hat.com>, Ingo Molnar <mingo@...hat.com>,
        Christoph Hellwig <hch@....de>,
        Al Viro <viro@...iv.linux.org.uk>,
        Thomas Gleixner <tglx@...utronix.de>,
        Matthew Wilcox <willy@...radead.org>,
        Jeff Smits <jeff.smits@...el.com>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] libnvdimm/pmem: Bypass CONFIG_HARDENED_USERCOPY overhead

From: Kees Cook
> Sent: 17 May 2019 16:54
...
> > I've changed some of our code to use __get_user() to avoid
> > these stupid overheads.
> 
> __get_user() skips even access_ok() checking too, so that doesn't seem
> like a good idea. Did you run access_ok() checks separately? (This
> generally isn't recommended.)

Of course, I'm not THAT stupid :-)

	David

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