On Wed, Jul 02 2014, David Laight <David.Laight@xxxxxxxxxx> wrote: > From: Michal Nazarewicz > ... >> > Alternatively it shouldn't be 'packed', and a full audit of the >> > other structures done to determine which ones can ever be misaligned >> > and then determine whether that should actually be allowed. >> >> All of the structures describe a wire protocol, whether we thing the >> structure can be allowed or not is inconsequential since that's what is >> being used. All of those structures must be packed. > > That just isn't true. > Just because a structure maps a protocol packet doesn't mean it has > to be 'packed'. > The TCP stack doesn't mark anything 'packed'. > It relies on the ethernet driver correctly aligning receive messages. Unfortunately in USB even if the message is correctly aligned, the fields in descriptors do not have to be. Furthermore, descriptors are stacked one after another and they rarely are multiply of four (or even two) bytes. usb_config_descriptor for example is 9 bytes. -- Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o ..o | Computer Science, Michał “mina86” Nazarewicz (o o) ooo +--<mpn@xxxxxxxxxx>--<xmpp:mina86@xxxxxxxxxx>--ooO--(_)--Ooo-- -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
