linux-kernel - kmap_atomic in 2.6.20.x

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-next>] [day] [month] [year] [list]

Date:	Wed, 6 Jun 2007 20:03:14 +0300
From:	"Raz Ben-Jehuda(caro)" <raziebe@...il.com>
To:	"Linux Kernel" <linux-kernel@...r.kernel.org>
Subject: kmap_atomic in 2.6.20.x

Hello

I am running into some problems with kmap_atomic in my driver.
My driver copies some pages coming from
user space to "kernel space kmalloc'ed memory".
I had this code running from 2.6.5 to 2.6.17 without any problems.
I have upgraded to 2.6.20.xx and this code fails to kmap_atomic.
I am running a uni processor 2 GRAM machine, 32bit.

Basically this is code does:

get_user_pages(page,...)

kmap_atomic(page,KM_USER0);
 .. copy and stuff
kunmap_atomic(page,KM_USER0)

I have also tried KM_USER1 and KM_SKB_SUNRPC_DATA.
I crash in arch/i386/highmem.c line 42:
  ...
  if (!pte_none(*(kmap_pte-idx)))
                  BUG();
..

To the best of my understanding ( from "see : understand the linux
kernel" page 310 ) , a different kernel component holds this window. A
fact which is quite strange in the case of KM_SKB_SUNRPC_DATA. I have
nothing that uses it.

1. Why kmap_atomic does not return NULL ?
2. Why am I failing only in high memory mappings ?

-- 
Raz
-
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/