Date: Sat, 5 Jul 2014 21:05:52 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Julian Elischer <julian@freebsd.org> Cc: freebsd-fs@freebsd.org, Stefan Parvu <sparvu@systemdatarecorder.org>, FreeBSD Hackers <freebsd-hackers@freebsd.org>, Roger Pau Monn? <roger.pau@citrix.com> Subject: Re: Strange IO performance with UFS Message-ID: <20140705180552.GT93733@kib.kiev.ua> In-Reply-To: <53B80A97.1080803@freebsd.org> References: <53B691EA.3070108@citrix.com> <53B69C73.7090806@citrix.com> <20140705001938.54a3873dd698080d93d840e2@systemdatarecorder.org> <53B7C616.1000702@citrix.com> <20140705095831.GO93733@kib.kiev.ua> <53B7D4DF.40301@citrix.com> <20140705112448.GQ93733@kib.kiev.ua> <53B80A97.1080803@freebsd.org>
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--oFYJDJkv0E+Y9r9L Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Jul 05, 2014 at 10:24:23PM +0800, Julian Elischer wrote: > On 7/5/14, 7:24 PM, Konstantin Belousov wrote: > > This leaves the unwritten portion of the block with the garbage. I > > believe that it is not harmful, since the only way for usermode to > > access that garbage is through the mmap(2). The vnode_generic_getpages() > > zeroes out parts of the page which are after EOF. >=20 > I have vague memories of this being in a security bulletin once along=20 > the lines of "random data disclosure" by making tons of 1 frag size=20 > files and then mmapping them. I am not sure what do you reference there. Might be, http://www.freebsd.org/security/advisories/FreeBSD-SA-13:11.sendfile.asc ? --oFYJDJkv0E+Y9r9L Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBAgAGBQJTuD5/AAoJEJDCuSvBvK1BoLAP/jSqameKVZxTczf3CNW1f1OT U3wY3Dad+2ymwVmNkF6k5Rq4rFKfYOSt/DJflGMzC8FWCNFdrm3iCW0H3shMEYSQ Eugjui+f0XrtDj+8t65ngmiBPJ4Jp8/uDoTs2ZlYl+psx3HJ+VZtRo928sHePG9O oBZLlPUcA7ZGmrsflWJRIbZbi3MyHgvIg/h3pRzvO02MD5yMvuJBB/KAhRlHtgap Bi4aRaDfGE3XyL/+3DCnViAZNuyKP9JnPPlTUfXsMbaNxCeNoUtSnR+UrzhXsACH 2iLvSbVX19zN8q1yNbvMWOgfeonXnx8fbvjnkH7BByyaPsqwYeKCNTqBVGmK0oL8 DsOjGk6yDHb3fZrf1wlqdGGZ/9WgHZlRaBHvsweoYu/4Q2w4IoQNW55k5bq4DKAP PJIxzIE4GUozANhg1q+V0kzpUMNJHaPFlWJnn9Nld1NVU91LJ1LHdzDzivsaUujP 9TUXaQTlB43m+k7JruqyFCUbMmqSXSlUmG+y8K/FECs+LWe9sRYW6UruoLUkUAE2 fjtPZbmtkGWo+h9ILPu63g5E5QWxLHaBzk4lUu9KZYigQTpW0DAMVMIwnZgVhm+p 04bmvvJfg6gVqHHmqz9+ef5gkg/eHCedos8dBaE2HuBbar4QVI0wI49z60esiwvy iymUu+RPNEvPynC4Tw1W =whGv -----END PGP SIGNATURE----- --oFYJDJkv0E+Y9r9L--
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