linux-kernel - Re: [patch 5/6] ps3: BD/DVD/CD-ROM Storage Driver

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: <1184331741.3402.13.camel@localhost.localdomain>
Date:	Fri, 13 Jul 2007 09:02:21 -0400
From:	James Bottomley <James.Bottomley@...elEye.com>
To:	Geert Uytterhoeven <Geert.Uytterhoeven@...ycom.com>
Cc:	Paul Mackerras <paulus@...ba.org>, Jens Axboe <axboe@...nel.dk>,
	Alessandro Rubini <rubini@...ion.unipv.it>,
	linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org,
	linux-scsi@...r.kernel.org,
	Geoff Levand <geoffrey.levand@...sony.com>
Subject: Re: [patch 5/6] ps3: BD/DVD/CD-ROM Storage Driver

On Wed, 2007-07-04 at 15:22 +0200, Geert Uytterhoeven wrote:
> +                       kaddr = kmap_atomic(sgpnt->page, KM_USER0);
> +                       if (!kaddr)
> +                               return -1;
> +                       len = sgpnt->length;
> +                       if ((req_len + len) > buflen) {
> +                               active = 0;
> +                               len = buflen - req_len;
> +                       }
> +                       memcpy(kaddr + sgpnt->offset, buf + req_len,
> len);
> +                       kunmap_atomic(kaddr, KM_USER0);

This isn't a SCSI objection, but this sequence appears several times in
this driver.  It's wrong for a non-PIPT architecture (and I believe the
PS3 is VIPT) because you copy into the kernel alias for the page, which
dirties the line in the cache of that alias (the user alias cache line
was already invalidated).  However, unless you flush the kernel alias to
main memory, the user could read stale data.  The way this is supposed
to be done is to do a 

flush_kernel_dcache_page(kaddr)

before doing the kunmap.

Otherwise it looks OK from the SCSI point of view.

James


-
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/