linux-kernel - Re: __getblk infinite loop

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: <b6c5339f0809050758r8ba7559k4ebe56531f5556e6@mail.gmail.com>
Date:	Fri, 5 Sep 2008 10:58:55 -0400
From:	"Bob Copeland" <me@...copeland.com>
To:	"Andrew Morton" <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, snakebyte@....de
Subject: Re: __getblk infinite loop

On Fri, Sep 5, 2008 at 1:38 AM, Andrew Morton <akpm@...ux-foundation.org> wrote:
> That loop does lock up on people occasionally - last time was in isofs,
> because it had done an insane set_blocksize() earlier on.
>
> Yes, it's always a case of garbage in, garbage out (or nothing out, as
> the case may be).
>
> No, it's not particularly programmer-friendly behaviour.

Ok, I think I get it now - sector_t 0x1d4000004 is in the addressable
range (by one bit) since we can address 4G blocks of PAGE_SIZE and the
FS is using a block size of 2048.  grow_buffers() always returns 0
because find_or_create_page() fails adding a page with that huge
offset into the pagecache (?), so we try to free memory and try again.
 Your patch here:

    http://marc.info/?l=linux-kernel&m=117202372525279&w=2

doesn't apply to the situation since index is still technically a
valid page offset.

So, I guess the answer is to deal with it in fsck and tell people
"don't do that."
-- 
Bob Copeland %% www.bobcopeland.com
--
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/