Re: + futex-avoid-kernel-taint-caused-by-get_robust_list.patch added to -mm tree

Re: + futex-avoid-kernel-taint-caused-by-get_robust_list.patch added to -mm tree

[Richard Weinberger]

Am Fri, 15 Feb 2013 14:26:52 -0800
schrieb akpm@linux-foundation.org:
> ------------------------------------------------------
> From: Paul Gortmaker <paul.gortmaker@windriver.com>
> Subject: futex: avoid kernel taint caused by get_robust_list
> 
> Commit ec0c4274e33c0373e4 ("futex: Mark get_robust_list as
> deprecated") added these two WARN_ONCE calls.
> 
> However, WARN_ONCE taints the kernel, and we shouldn't be allowing any
> user who wanders by to do this.  For example, the system fuzzer
> "trinity" uses the tainted state as a metric for when to stop,
> assuming that it has caused significant wreckage (and indeed that
> tool is what actually led me to this change).
> 
> The ability to deprecate this code has been called into question[1],
> but if that remains to be finalized, then making this change in the
> interim seems to make sense.

Do we really want to remove this system call in 2013?
Note, Documentation/feature-removal-schedule.txt is gone...

CRIU folks, I guess you still need the call?
Or have you found an alternative way to get the robost list?

As stated in [0], I'd simply revert commit ec0c4274 ("futex: Mark
get_robust_list as deprecated")

Thanks,
//richard

[0] http://permalink.gmane.org/gmane.linux.kernel.hardened.devel/506

Re: + futex-avoid-kernel-taint-caused-by-get_robust_list.patch added to -mm tree

[Andrew Morton]

On Fri, 15 Feb 2013 23:44:44 +0100
Richard Weinberger <richard@nod.at> wrote:

> As stated in [0], I'd simply revert commit ec0c4274 ("futex: Mark
> get_robust_list as deprecated")

Too much talk, not enough patches.  I typed it all in again.

Re: + futex-avoid-kernel-taint-caused-by-get_robust_list.patch added to -mm tree

[Cyrill Gorcunov]

On Fri, Feb 15, 2013 at 11:44:44PM +0100, Richard Weinberger wrote:
> > The ability to deprecate this code has been called into question[1],
> > but if that remains to be finalized, then making this change in the
> > interim seems to make sense.
> 
> Do we really want to remove this system call in 2013?
> Note, Documentation/feature-removal-schedule.txt is gone...
> 
> CRIU folks, I guess you still need the call?
> Or have you found an alternative way to get the robost list?

Yes, we need this call and we use it.

> As stated in [0], I'd simply revert commit ec0c4274 ("futex: Mark
> get_robust_list as deprecated")

Thanks!

Re: + futex-avoid-kernel-taint-caused-by-get_robust_list.patch added to -mm tree

[Thomas Gleixner]

On Sat, 16 Feb 2013, Cyrill Gorcunov wrote:

> On Fri, Feb 15, 2013 at 11:44:44PM +0100, Richard Weinberger wrote:
> > > The ability to deprecate this code has been called into question[1],
> > > but if that remains to be finalized, then making this change in the
> > > interim seems to make sense.
> > 
> > Do we really want to remove this system call in 2013?
> > Note, Documentation/feature-removal-schedule.txt is gone...
> > 
> > CRIU folks, I guess you still need the call?
> > Or have you found an alternative way to get the robost list?
> 
> Yes, we need this call and we use it.
> 
> > As stated in [0], I'd simply revert commit ec0c4274 ("futex: Mark
> > get_robust_list as deprecated")
> 
> Thanks!

I take the revert via tip and queue it for 3.9

Thanks,

	tglx