linux-kernel - Re: [PATCH][BUG] Incorrect SCSI transfer length computation from odd sized scsi_execute

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]

Date:	Wed, 11 Jul 2007 20:19:54 -0500
From:	Mike Christie <michaelc@...wisc.edu>
To:	Jeremy Linton <jli@...shamstorage.com>
CC:	James Bottomley <James.Bottomley@...elEye.com>,
	Linux Scsi <linux-scsi@...r.kernel.org>,
	Linux Kernel List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH][BUG] Incorrect SCSI transfer length computation from
 odd sized scsi_execute_async() transfers.

Jeremy Linton wrote:
> Any function which use scsi_execute_async() and transfers "odd" sized 
> data that doesn't align correctly with the segment sizes may have its 
> transfer length padded out to the closest segment size.
> 
> For writes, this results in unnecessary data being transfered to the 
> SCSI target. For reads, it affects the residual data length being 
> returned to the application since the residual length will be based on 
> the padded transfer size rather than the actual request size.
> 
> The easiest way to see this is by trying to read using the SG_IO ioctl a 
> large (>32k) buffer size from a tape device that only has a few bytes of 
> data stored for the current block. The resulting resid will generally be 
> incorrect.
> 
> I've fixed this simply by changing scsi_req_map_sg() so that it places 
> the requested transfer length in rq->data_len rather than the sum of all 
> the sg segments.
> 
> This patch applies against scsi_lib.c in 2.6.22.
> 
> Signed-off-by: Jeremy Linton <jli@...shamstorage.com>
> 
> 
> --- linux-2.6.22/drivers/scsi/scsi_lib.c.orig   2007-07-11 
> 19:07:06.000000000 -0500
> +++ linux-2.6.22/drivers/scsi/scsi_lib.c        2007-07-11 
> 18:43:36.000000000 -0500
> @@ -350,7 +350,7 @@ static int scsi_req_map_sg(struct reques
>         }
> 
>         rq->buffer = rq->data = NULL;
> -       rq->data_len = data_len;
> +       rq->data_len = bufflen;
>         return 0;
> 

I think you needed some other bits in there. See this patch 
http://marc.info/?l=linux-scsi&m=117392208211297&w=2

I tried just setting the bufflen first, and that still had problems. 
Could you try the patch here

http://marc.info/?l=linux-scsi&m=117392208211297&w=2
-
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/