linux-kernel - Re: [PATCH 1/5] zram: handle multiple pages attached bio's bvec

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:   Tue, 4 Apr 2017 13:55:09 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Minchan Kim <minchan@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        kernel-team@....com, Jens Axboe <axboe@...nel.dk>,
        Hannes Reinecke <hare@...e.com>,
        Johannes Thumshirn <jthumshirn@...e.de>
Subject: Re: [PATCH 1/5] zram: handle multiple pages attached bio's bvec

On (04/03/17 14:17), Minchan Kim wrote:
> Johannes Thumshirn reported system goes the panic when using NVMe over
> Fabrics loopback target with zram.
> 
> The reason is zram expects each bvec in bio contains a single page
> but nvme can attach a huge bulk of pages attached to the bio's bvec
> so that zram's index arithmetic could be wrong so that out-of-bound
> access makes panic.
> 
> It can be solved by limiting max_sectors with SECTORS_PER_PAGE like
> [1] but it makes zram slow because bio should split with each pages
> so this patch makes zram aware of multiple pages in a bvec so it
> could solve without any regression.
> 
> [1] 0bc315381fe9, zram: set physical queue limits to avoid array out of
>     bounds accesses
> 
> Cc: Jens Axboe <axboe@...nel.dk>
> Cc: Hannes Reinecke <hare@...e.com>
> Reported-by: Johannes Thumshirn <jthumshirn@...e.de>
> Tested-by: Johannes Thumshirn <jthumshirn@...e.de>
> Reviewed-by: Johannes Thumshirn <jthumshirn@...e.de>
> Signed-off-by: Johannes Thumshirn <jthumshirn@...e.de>
> Signed-off-by: Minchan Kim <minchan@...nel.org>

Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>


> +		unsigned int remained = bvec.bv_len;
...
> +		} while (remained);

a tiny nitpick,  "-ed" in variable name looks a bit unusual.

	-ss