lkml.org 
[lkml]   [2001]   [May]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: SMP races in proc with thread_struct
From
Date
Keith Owens <kaos@ocs.com.au> writes:

|> On Fri, 04 May 2001 07:34:20 -0500,
|> Todd Inglett <tinglett@vnet.ibm.com> wrote:
|> >But this is where hell breaks loose. Every process has a valid parent
|> >-- unless it is dead and nobody cares. Process N has already exited and
|> >released from the tasklist while its parent was still alive. There was
|> >no reason to reparent it. It just got released. So N's task_struct has
|> >a dangling ptr to its parent. Nobody is holding the parent task_struct,
|> >either. When the parent died memory for its task_struct was released.
|> >This is ungood.
|>
|> Wrap the reference to the parent task structure with exception table
|> recovery code, like copy_from_user().

Exception tables only protect accesses to user virtual memory. Kernel
memory references must always be valid in the first place.

Andreas.

--
Andreas Schwab "And now for something
SuSE Labs completely different."
Andreas.Schwab@suse.de
SuSE GmbH, Schanzäckerstr. 10, D-90443 Nürnberg
Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
-
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 12:52    [W:0.065 / U:2.808 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site