linux-kernel - vmalloc problem with DEBUG

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>] [day] [month] [year] [list]

Date:	Tue, 27 May 2008 09:51:04 +0200
From:	"Zdenek Kabelac" <zdenek.kabelac@...il.com>
To:	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Cc:	ak@....de
Subject: vmalloc problem with DEBUG_PAGEALLOC config option

Hello

Recently I've spent some time with hunting weird problem which
appeared to be caused by the CONFIG_DEBUG_PAGEALLOC option. After the
crash of 'nash' sometimes my application started to behave strange -
after some debugging and testing when I've basically tried everything
else :) because it wouldn't come to my mind what could be wrong I' ve
noticed, that inside the kernel driver 'vmalloc-ated' memory chunk
simply doesn't get the right memory copy from the funtion call
copy_from_user().
When I want to get 16kb copied from user space and I prefil it with
some byte pattern, I get zeroed area. When I use 'get_user()'  I see
correct user-space data - so the problem is with the copying and
DEBUG_PAGEALLOC enabled.

When I'm not using this debug option - I'm not able to replicate my
problem with copy_from_user().

I'm using 64bit x86 kernel on 2GB T61

Zdenek
--
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/