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

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

[akpm]

The patch titled
     Subject: futex: avoid kernel taint caused by get_robust_list
has been added to the -mm tree.  Its filename is
     futex-avoid-kernel-taint-caused-by-get_robust_list.patch

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------------------------------------------------------
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.

[1] http://lkml.indiana.edu/hypermail/linux/kernel/1208.0/01081.html

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>	[3.4+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/futex.c        |    2 +-
 kernel/futex_compat.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff -puN kernel/futex.c~futex-avoid-kernel-taint-caused-by-get_robust_list kernel/futex.c
--- a/kernel/futex.c~futex-avoid-kernel-taint-caused-by-get_robust_list
+++ a/kernel/futex.c
@@ -2472,7 +2472,7 @@ SYSCALL_DEFINE3(get_robust_list, int, pi
 	if (!futex_cmpxchg_enabled)
 		return -ENOSYS;
 
-	WARN_ONCE(1, "deprecated: get_robust_list will be deleted in 2013.\n");
+	printk_once(KERN_WARNING "deprecated: get_robust_list will be deleted in 2013.\n");
 
 	rcu_read_lock();
 
diff -puN kernel/futex_compat.c~futex-avoid-kernel-taint-caused-by-get_robust_list kernel/futex_compat.c
--- a/kernel/futex_compat.c~futex-avoid-kernel-taint-caused-by-get_robust_list
+++ a/kernel/futex_compat.c
@@ -143,7 +143,7 @@ COMPAT_SYSCALL_DEFINE3(get_robust_list, 
 	if (!futex_cmpxchg_enabled)
 		return -ENOSYS;
 
-	WARN_ONCE(1, "deprecated: get_robust_list will be deleted in 2013.\n");
+	printk_once(KERN_WARNING "deprecated: get_robust_list will be deleted in 2013.\n");
 
 	rcu_read_lock();
 
_

Patches currently in -mm which might be from paul.gortmaker@windriver.com are

linux-next.patch
compiler-gcc4h-reorder-macros-based-upon-gcc-ver.patch
compiler-gcch-add-gcc-recommended-gcc_version-macro.patch
compiler-gcc34h-use-gcc_version-macro.patch
compiler-gcc4h-bugh-remove-duplicate-macros.patch
bugh-fix-build_bug_on-macro-in-__checker__.patch
bugh-prevent-double-evaulation-of-in-build_bug_on.patch
bugh-make-build_bug_on-generate-compile-time-error.patch
compilerh-bugh-prevent-double-error-messages-with-build_bug_on.patch
bugh-compilerh-introduce-compiletime_assert-build_bug_on_msg.patch
inotify-remove-broken-mask-checks-causing-unmount-to-be-einval.patch
time-dont-inline-export_symbol-functions.patch
dca-convert-to-idr_alloc.patch
futex-avoid-kernel-taint-caused-by-get_robust_list.patch

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