lkml.org 
[lkml]   [2002]   [Aug]   [6]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
DateTue, 06 Aug 2002 02:28:13 -0700 (PDT)
SubjectRe: [TRIVIAL] Warn users about machines with non-working WP bit
From"David S. Miller" <>
   From: Manfred Spraul <manfred@colorfullife.com>
   Date: Tue, 06 Aug 2002 11:17:33 +0200

   > -		printk("No.\n");
   > +		printk("No (that's security hole).\n");
   >  #ifdef CONFIG_X86_WP_WORKS_OK
   Could you explain the hole?
   WP works for user space apps, only ring0 (or ring 0-2?) code
   ignores the WP bit on i386.

So copy_to_user() could write to user areas that are write-proteced.

verify_area() checks aren't enough, consider a threaded application
calling mprotect() while the copy is in progress.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:22    [W:4.727 / U:0.020 seconds]
©2003-2008 Jasper Spaans