linux-kernel - Re: USB mass storage and ARM cache coherency

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1266401881.16346.278.camel@pasglop>
Date:	Wed, 17 Feb 2010 21:18:01 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Oliver Neukum <oliver@...kum.org>
Cc:	"Shilimkar, Santosh" <santosh.shilimkar@...com>,
	Matthew Dharm <mdharm-kernel@...-eyed-alien.net>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Ming Lei <tom.leiming@...il.com>,
	"Mankad, Maulik Ojas" <x0082077@...com>,
	Sergei Shtylyov <sshtylyov@...mvista.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Sebastian Siewior <bigeasy@...utronix.de>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Pavel Machek <pavel@....cz>, Greg KH <greg@...ah.com>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: USB mass storage and ARM cache coherency

On Wed, 2010-02-17 at 11:09 +0100, Oliver Neukum wrote:
> 
> No problem here. USB core does the mapping only if the low-level driver
> so requests. The only exception is in usb_buffer_alloc(), but that boils
> down to dma_alloc_coherent() 

Allright, so why do we need to "fix" anything ? Or is the whole thread
moot ? :-)

It's pretty clear that between dma_map* and subsequent unmap, the memory
is owned by the device and must not be touched by the CPU. If that is
violated, then we have a driver bug.

Cheers,
Ben.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/