[PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume

[PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume

[Josh Poimboeuf]

Resuming from a suspend operation is showing a KASAN false positive
warning:

  BUG: KASAN: stack-out-of-bounds in unwind_get_return_address+0x11d/0x130 at addr ffff8803867d7878
  Read of size 8 by task pm-suspend/7774
  page:ffffea000e19f5c0 count:0 mapcount:0 mapping:          (null) index:0x0
  flags: 0x2ffff0000000000()
  page dumped because: kasan: bad access detected
  CPU: 0 PID: 7774 Comm: pm-suspend Tainted: G    B           4.9.0-rc7+ #8
  Hardware name: Gigabyte Technology Co., Ltd. Z170X-UD5/Z170X-UD5-CF, BIOS F5 03/07/2016
   ffff8803867d7468 ffffffffb4c0d051 ffff8803867d7500 ffff8803867d7878
   ffff8803867d74f0 ffffffffb45cbe34 ffffffffb4e64136 ffffffffb4510d42
   ffff8803828c3f4c 0000000000000097 0000000041b58ab3 ffffffffb6192731
  Call Trace:
    dump_stack+0x63/0x82
    kasan_report_error+0x4b4/0x4e0
    ? acpi_hw_read_port+0xd0/0x1ea
    ? kfree_const+0x22/0x30
    ? acpi_hw_validate_io_request+0x1a6/0x1a6
    __asan_report_load8_noabort+0x61/0x70
    ? unwind_get_return_address+0x11d/0x130
    unwind_get_return_address+0x11d/0x130
    ? unwind_next_frame+0x97/0xf0
    __save_stack_trace+0x92/0x100
    save_stack_trace+0x1b/0x20
    save_stack+0x46/0xd0
    ? save_stack_trace+0x1b/0x20
    ? save_stack+0x46/0xd0
    ? kasan_kmalloc+0xad/0xe0
    ? kasan_slab_alloc+0x12/0x20
    ? acpi_hw_read+0x2b6/0x3aa
    ? acpi_hw_validate_register+0x20b/0x20b
    ? acpi_hw_write_port+0x72/0xc7
    ? acpi_hw_write+0x11f/0x15f
    ? acpi_hw_read_multiple+0x19f/0x19f
    ? memcpy+0x45/0x50
    ? acpi_hw_write_port+0x72/0xc7
    ? acpi_hw_write+0x11f/0x15f
    ? acpi_hw_read_multiple+0x19f/0x19f
    ? kasan_unpoison_shadow+0x36/0x50
    kasan_kmalloc+0xad/0xe0
    kasan_slab_alloc+0x12/0x20
    kmem_cache_alloc_trace+0xbc/0x1e0
    ? acpi_get_sleep_type_data+0x9a/0x578
    acpi_get_sleep_type_data+0x9a/0x578
    acpi_hw_legacy_wake_prep+0x88/0x22c
    ? acpi_hw_legacy_sleep+0x3c7/0x3c7
    ? acpi_write_bit_register+0x28d/0x2d3
    ? acpi_read_bit_register+0x19b/0x19b
    acpi_hw_sleep_dispatch+0xb5/0xba
    acpi_leave_sleep_state_prep+0x17/0x19
    acpi_suspend_enter+0x154/0x1e0
    ? trace_suspend_resume+0xe8/0xe8
    suspend_devices_and_enter+0xb09/0xdb0
    ? printk+0xa8/0xd8
    ? arch_suspend_enable_irqs+0x20/0x20
    ? try_to_freeze_tasks+0x295/0x600
    pm_suspend+0x6c9/0x780
    ? finish_wait+0x1f0/0x1f0
    ? suspend_devices_and_enter+0xdb0/0xdb0
    state_store+0xa2/0x120
    ? kobj_attr_show+0x60/0x60
    kobj_attr_store+0x36/0x70
    sysfs_kf_write+0x131/0x200
    kernfs_fop_write+0x295/0x3f0
    __vfs_write+0xef/0x760
    ? handle_mm_fault+0x1346/0x35e0
    ? do_iter_readv_writev+0x660/0x660
    ? __pmd_alloc+0x310/0x310
    ? do_lock_file_wait+0x1e0/0x1e0
    ? apparmor_file_permission+0x18/0x20
    ? security_file_permission+0x73/0x1c0
    ? rw_verify_area+0xbd/0x2b0
    vfs_write+0x149/0x4a0
    SyS_write+0xd9/0x1c0
    ? SyS_read+0x1c0/0x1c0
    entry_SYSCALL_64_fastpath+0x1e/0xad
  Memory state around the buggy address:
   ffff8803867d7700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
   ffff8803867d7780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  >ffff8803867d7800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f4
                                                                  ^
   ffff8803867d7880: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
   ffff8803867d7900: 00 00 00 f1 f1 f1 f1 04 f4 f4 f4 f3 f3 f3 f3 00

KASAN instrumentation poisons the stack when entering a function and
unpoisons it when exiting the function.  However, in the suspend path,
some functions never return, so their stack never gets unpoisoned,
resulting in stale KASAN shadow data which can cause false positive
warnings like the one above.

Reported-by: Scott Bauer <scott.bauer@intel.com>
Tested-by: Scott Bauer <scott.bauer@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 arch/x86/kernel/acpi/sleep.c | 3 +++
 include/linux/kasan.h        | 7 +++++++
 2 files changed, 10 insertions(+)

diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index 4858733..62bd046 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -115,6 +115,9 @@ int x86_acpi_suspend_lowlevel(void)
 	pause_graph_tracing();
 	do_suspend_lowlevel();
 	unpause_graph_tracing();
+
+	kasan_unpoison_stack_below_sp();
+
 	return 0;
 }
 
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 820c0ad..e0945d5 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -45,6 +45,12 @@ void kasan_unpoison_shadow(const void *address, size_t size);
 
 void kasan_unpoison_task_stack(struct task_struct *task);
 void kasan_unpoison_stack_above_sp_to(const void *watermark);
+asmlinkage void kasan_unpoison_task_stack_below(const void *watermark);
+
+static inline void kasan_unpoison_stack_below_sp(void)
+{
+	kasan_unpoison_task_stack_below(__builtin_frame_address(0));
+}
 
 void kasan_alloc_pages(struct page *page, unsigned int order);
 void kasan_free_pages(struct page *page, unsigned int order);
@@ -87,6 +93,7 @@ static inline void kasan_unpoison_shadow(const void *address, size_t size) {}
 
 static inline void kasan_unpoison_task_stack(struct task_struct *task) {}
 static inline void kasan_unpoison_stack_above_sp_to(const void *watermark) {}
+static inline void kasan_unpoison_stack_below_sp(void) {}
 
 static inline void kasan_enable_current(void) {}
 static inline void kasan_disable_current(void) {}
-- 
2.7.4

Re: [PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume

[Andrey Ryabinin]

On 12/01/2016 02:10 AM, Josh Poimboeuf wrote:
> Resuming from a suspend operation is showing a KASAN false positive
> warning:
> 

> KASAN instrumentation poisons the stack when entering a function and
> unpoisons it when exiting the function.  However, in the suspend path,
> some functions never return, so their stack never gets unpoisoned,
> resulting in stale KASAN shadow data which can cause false positive
> warnings like the one above.
> 
> Reported-by: Scott Bauer <scott.bauer@intel.com>
> Tested-by: Scott Bauer <scott.bauer@intel.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> ---
>  arch/x86/kernel/acpi/sleep.c | 3 +++
>  include/linux/kasan.h        | 7 +++++++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
> index 4858733..62bd046 100644
> --- a/arch/x86/kernel/acpi/sleep.c
> +++ b/arch/x86/kernel/acpi/sleep.c
> @@ -115,6 +115,9 @@ int x86_acpi_suspend_lowlevel(void)
>  	pause_graph_tracing();
>  	do_suspend_lowlevel();
>  	unpause_graph_tracing();
> +
> +	kasan_unpoison_stack_below_sp();
> +

I think this might be too late. We may hit stale poison in the first C function called
after resume (restore_processor_state()). Thus the shadow must be unpoisoned prior such call,
i.e. somewhere in do_suspend_lowlevel() after .Lresume_point.

Re: [PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume

[Josh Poimboeuf]

On Thu, Dec 01, 2016 at 12:05:34PM +0300, Andrey Ryabinin wrote:
> 
> 
> On 12/01/2016 02:10 AM, Josh Poimboeuf wrote:
> > Resuming from a suspend operation is showing a KASAN false positive
> > warning:
> > 
> 
> > KASAN instrumentation poisons the stack when entering a function and
> > unpoisons it when exiting the function.  However, in the suspend path,
> > some functions never return, so their stack never gets unpoisoned,
> > resulting in stale KASAN shadow data which can cause false positive
> > warnings like the one above.
> > 
> > Reported-by: Scott Bauer <scott.bauer@intel.com>
> > Tested-by: Scott Bauer <scott.bauer@intel.com>
> > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> > ---
> >  arch/x86/kernel/acpi/sleep.c | 3 +++
> >  include/linux/kasan.h        | 7 +++++++
> >  2 files changed, 10 insertions(+)
> > 
> > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
> > index 4858733..62bd046 100644
> > --- a/arch/x86/kernel/acpi/sleep.c
> > +++ b/arch/x86/kernel/acpi/sleep.c
> > @@ -115,6 +115,9 @@ int x86_acpi_suspend_lowlevel(void)
> >  	pause_graph_tracing();
> >  	do_suspend_lowlevel();
> >  	unpause_graph_tracing();
> > +
> > +	kasan_unpoison_stack_below_sp();
> > +
> 
> I think this might be too late. We may hit stale poison in the first C function called
> after resume (restore_processor_state()). Thus the shadow must be unpoisoned prior such call,
> i.e. somewhere in do_suspend_lowlevel() after .Lresume_point.

Yeah, I think you're right.  Will spin a v2.

-- 
Josh

Re: [PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume

[Josh Poimboeuf]

On Thu, Dec 01, 2016 at 08:58:21AM -0600, Josh Poimboeuf wrote:
> On Thu, Dec 01, 2016 at 12:05:34PM +0300, Andrey Ryabinin wrote:
> > 
> > 
> > On 12/01/2016 02:10 AM, Josh Poimboeuf wrote:
> > > Resuming from a suspend operation is showing a KASAN false positive
> > > warning:
> > > 
> > 
> > > KASAN instrumentation poisons the stack when entering a function and
> > > unpoisons it when exiting the function.  However, in the suspend path,
> > > some functions never return, so their stack never gets unpoisoned,
> > > resulting in stale KASAN shadow data which can cause false positive
> > > warnings like the one above.
> > > 
> > > Reported-by: Scott Bauer <scott.bauer@intel.com>
> > > Tested-by: Scott Bauer <scott.bauer@intel.com>
> > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> > > ---
> > >  arch/x86/kernel/acpi/sleep.c | 3 +++
> > >  include/linux/kasan.h        | 7 +++++++
> > >  2 files changed, 10 insertions(+)
> > > 
> > > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
> > > index 4858733..62bd046 100644
> > > --- a/arch/x86/kernel/acpi/sleep.c
> > > +++ b/arch/x86/kernel/acpi/sleep.c
> > > @@ -115,6 +115,9 @@ int x86_acpi_suspend_lowlevel(void)
> > >  	pause_graph_tracing();
> > >  	do_suspend_lowlevel();
> > >  	unpause_graph_tracing();
> > > +
> > > +	kasan_unpoison_stack_below_sp();
> > > +
> > 
> > I think this might be too late. We may hit stale poison in the first C function called
> > after resume (restore_processor_state()). Thus the shadow must be unpoisoned prior such call,
> > i.e. somewhere in do_suspend_lowlevel() after .Lresume_point.
> 
> Yeah, I think you're right.  Will spin a v2.

So I tried calling kasan_unpoison_task_stack_below() from
do_suspend_lowlevel(), but it hung on the resume.  Presumably because
restore_processor_state() does some important setup which would be
needed before calling into kasan_unpoison_task_stack_below().  For
example, setting up the gs register.  So it's a bit of a catch-22.

It could probably be fixed properly by rewriting do_suspend_lowlevel()
to call restore_processor_state() with the temporary stack before
switching to the original stack and doing the unpoison.

(And there are some other issues with do_suspend_lowlevel() and I'd love
to try taking a scalpel to it.  But I have too many knives in the air
already to want to try to attempt that right now...)

Unless somebody else wants to take a stab at it, my original patch is
probably good enough for now, since restore_processor_state() doesn't
seem to be triggering any KASAN warnings.

-- 
Josh

Re: [PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume

[Dmitry Vyukov]

On Thu, Dec 1, 2016 at 5:45 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> On Thu, Dec 01, 2016 at 08:58:21AM -0600, Josh Poimboeuf wrote:
>> On Thu, Dec 01, 2016 at 12:05:34PM +0300, Andrey Ryabinin wrote:
>> >
>> >
>> > On 12/01/2016 02:10 AM, Josh Poimboeuf wrote:
>> > > Resuming from a suspend operation is showing a KASAN false positive
>> > > warning:
>> > >
>> >
>> > > KASAN instrumentation poisons the stack when entering a function and
>> > > unpoisons it when exiting the function.  However, in the suspend path,
>> > > some functions never return, so their stack never gets unpoisoned,
>> > > resulting in stale KASAN shadow data which can cause false positive
>> > > warnings like the one above.
>> > >
>> > > Reported-by: Scott Bauer <scott.bauer@intel.com>
>> > > Tested-by: Scott Bauer <scott.bauer@intel.com>
>> > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
>> > > ---
>> > >  arch/x86/kernel/acpi/sleep.c | 3 +++
>> > >  include/linux/kasan.h        | 7 +++++++
>> > >  2 files changed, 10 insertions(+)
>> > >
>> > > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
>> > > index 4858733..62bd046 100644
>> > > --- a/arch/x86/kernel/acpi/sleep.c
>> > > +++ b/arch/x86/kernel/acpi/sleep.c
>> > > @@ -115,6 +115,9 @@ int x86_acpi_suspend_lowlevel(void)
>> > >   pause_graph_tracing();
>> > >   do_suspend_lowlevel();
>> > >   unpause_graph_tracing();
>> > > +
>> > > + kasan_unpoison_stack_below_sp();
>> > > +
>> >
>> > I think this might be too late. We may hit stale poison in the first C function called
>> > after resume (restore_processor_state()). Thus the shadow must be unpoisoned prior such call,
>> > i.e. somewhere in do_suspend_lowlevel() after .Lresume_point.
>>
>> Yeah, I think you're right.  Will spin a v2.
>
> So I tried calling kasan_unpoison_task_stack_below() from
> do_suspend_lowlevel(), but it hung on the resume.  Presumably because
> restore_processor_state() does some important setup which would be
> needed before calling into kasan_unpoison_task_stack_below().  For
> example, setting up the gs register.  So it's a bit of a catch-22.
>
> It could probably be fixed properly by rewriting do_suspend_lowlevel()
> to call restore_processor_state() with the temporary stack before
> switching to the original stack and doing the unpoison.
>
> (And there are some other issues with do_suspend_lowlevel() and I'd love
> to try taking a scalpel to it.  But I have too many knives in the air
> already to want to try to attempt that right now...)
>
> Unless somebody else wants to take a stab at it, my original patch is
> probably good enough for now, since restore_processor_state() doesn't
> seem to be triggering any KASAN warnings.

restore_processor_state/__restore_processor_state does not seem to
have any local variables, so KASAN does not do any stack checks there.
We could disable KASAN instrumentation of the file, or of particular
functions. Or we could call kasan_unpoison_shadow() on the stack range
before switching to it.

Re: [PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume

[Josh Poimboeuf]

On Thu, Dec 01, 2016 at 05:51:52PM +0100, Dmitry Vyukov wrote:
> On Thu, Dec 1, 2016 at 5:45 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > On Thu, Dec 01, 2016 at 08:58:21AM -0600, Josh Poimboeuf wrote:
> >> On Thu, Dec 01, 2016 at 12:05:34PM +0300, Andrey Ryabinin wrote:
> >> >
> >> >
> >> > On 12/01/2016 02:10 AM, Josh Poimboeuf wrote:
> >> > > Resuming from a suspend operation is showing a KASAN false positive
> >> > > warning:
> >> > >
> >> >
> >> > > KASAN instrumentation poisons the stack when entering a function and
> >> > > unpoisons it when exiting the function.  However, in the suspend path,
> >> > > some functions never return, so their stack never gets unpoisoned,
> >> > > resulting in stale KASAN shadow data which can cause false positive
> >> > > warnings like the one above.
> >> > >
> >> > > Reported-by: Scott Bauer <scott.bauer@intel.com>
> >> > > Tested-by: Scott Bauer <scott.bauer@intel.com>
> >> > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> >> > > ---
> >> > >  arch/x86/kernel/acpi/sleep.c | 3 +++
> >> > >  include/linux/kasan.h        | 7 +++++++
> >> > >  2 files changed, 10 insertions(+)
> >> > >
> >> > > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
> >> > > index 4858733..62bd046 100644
> >> > > --- a/arch/x86/kernel/acpi/sleep.c
> >> > > +++ b/arch/x86/kernel/acpi/sleep.c
> >> > > @@ -115,6 +115,9 @@ int x86_acpi_suspend_lowlevel(void)
> >> > >   pause_graph_tracing();
> >> > >   do_suspend_lowlevel();
> >> > >   unpause_graph_tracing();
> >> > > +
> >> > > + kasan_unpoison_stack_below_sp();
> >> > > +
> >> >
> >> > I think this might be too late. We may hit stale poison in the first C function called
> >> > after resume (restore_processor_state()). Thus the shadow must be unpoisoned prior such call,
> >> > i.e. somewhere in do_suspend_lowlevel() after .Lresume_point.
> >>
> >> Yeah, I think you're right.  Will spin a v2.
> >
> > So I tried calling kasan_unpoison_task_stack_below() from
> > do_suspend_lowlevel(), but it hung on the resume.  Presumably because
> > restore_processor_state() does some important setup which would be
> > needed before calling into kasan_unpoison_task_stack_below().  For
> > example, setting up the gs register.  So it's a bit of a catch-22.
> >
> > It could probably be fixed properly by rewriting do_suspend_lowlevel()
> > to call restore_processor_state() with the temporary stack before
> > switching to the original stack and doing the unpoison.
> >
> > (And there are some other issues with do_suspend_lowlevel() and I'd love
> > to try taking a scalpel to it.  But I have too many knives in the air
> > already to want to try to attempt that right now...)
> >
> > Unless somebody else wants to take a stab at it, my original patch is
> > probably good enough for now, since restore_processor_state() doesn't
> > seem to be triggering any KASAN warnings.
> 
> restore_processor_state/__restore_processor_state does not seem to
> have any local variables, so KASAN does not do any stack checks there.

Actually, looking at the object code, it uses a lot of stack space and
has several calls to __asan_report_load*() functions.  Probably due to
inlining of other functions which have stack variables.

> We could disable KASAN instrumentation of the file, or of particular
> functions.

I don't think that would be sufficient unless it were disabled for
__restore_processor_state() and all the functions it calls (and the
functions they call, etc), which wouldn't necessarily be
straightforward.

> Or we could call kasan_unpoison_shadow() on the stack range
> before switching to it.

I tried that already, but it hung because restore_processor_state()
hadn't been called yet (the catch-22 I mentioned aboved).

-- 
Josh

Re: [PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume

[Dmitry Vyukov]

On Thu, Dec 1, 2016 at 6:13 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> On Thu, Dec 01, 2016 at 05:51:52PM +0100, Dmitry Vyukov wrote:
>> On Thu, Dec 1, 2016 at 5:45 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
>> > On Thu, Dec 01, 2016 at 08:58:21AM -0600, Josh Poimboeuf wrote:
>> >> On Thu, Dec 01, 2016 at 12:05:34PM +0300, Andrey Ryabinin wrote:
>> >> >
>> >> >
>> >> > On 12/01/2016 02:10 AM, Josh Poimboeuf wrote:
>> >> > > Resuming from a suspend operation is showing a KASAN false positive
>> >> > > warning:
>> >> > >
>> >> >
>> >> > > KASAN instrumentation poisons the stack when entering a function and
>> >> > > unpoisons it when exiting the function.  However, in the suspend path,
>> >> > > some functions never return, so their stack never gets unpoisoned,
>> >> > > resulting in stale KASAN shadow data which can cause false positive
>> >> > > warnings like the one above.
>> >> > >
>> >> > > Reported-by: Scott Bauer <scott.bauer@intel.com>
>> >> > > Tested-by: Scott Bauer <scott.bauer@intel.com>
>> >> > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
>> >> > > ---
>> >> > >  arch/x86/kernel/acpi/sleep.c | 3 +++
>> >> > >  include/linux/kasan.h        | 7 +++++++
>> >> > >  2 files changed, 10 insertions(+)
>> >> > >
>> >> > > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
>> >> > > index 4858733..62bd046 100644
>> >> > > --- a/arch/x86/kernel/acpi/sleep.c
>> >> > > +++ b/arch/x86/kernel/acpi/sleep.c
>> >> > > @@ -115,6 +115,9 @@ int x86_acpi_suspend_lowlevel(void)
>> >> > >   pause_graph_tracing();
>> >> > >   do_suspend_lowlevel();
>> >> > >   unpause_graph_tracing();
>> >> > > +
>> >> > > + kasan_unpoison_stack_below_sp();
>> >> > > +
>> >> >
>> >> > I think this might be too late. We may hit stale poison in the first C function called
>> >> > after resume (restore_processor_state()). Thus the shadow must be unpoisoned prior such call,
>> >> > i.e. somewhere in do_suspend_lowlevel() after .Lresume_point.
>> >>
>> >> Yeah, I think you're right.  Will spin a v2.
>> >
>> > So I tried calling kasan_unpoison_task_stack_below() from
>> > do_suspend_lowlevel(), but it hung on the resume.  Presumably because
>> > restore_processor_state() does some important setup which would be
>> > needed before calling into kasan_unpoison_task_stack_below().  For
>> > example, setting up the gs register.  So it's a bit of a catch-22.
>> >
>> > It could probably be fixed properly by rewriting do_suspend_lowlevel()
>> > to call restore_processor_state() with the temporary stack before
>> > switching to the original stack and doing the unpoison.
>> >
>> > (And there are some other issues with do_suspend_lowlevel() and I'd love
>> > to try taking a scalpel to it.  But I have too many knives in the air
>> > already to want to try to attempt that right now...)
>> >
>> > Unless somebody else wants to take a stab at it, my original patch is
>> > probably good enough for now, since restore_processor_state() doesn't
>> > seem to be triggering any KASAN warnings.
>>
>> restore_processor_state/__restore_processor_state does not seem to
>> have any local variables, so KASAN does not do any stack checks there.
>
> Actually, looking at the object code, it uses a lot of stack space and
> has several calls to __asan_report_load*() functions.  Probably due to
> inlining of other functions which have stack variables.

That can be loads of heap variables (or other non-stack data). KASAN
will emit these checks for lots of loads, but they don't necessary go
to stack.


>> We could disable KASAN instrumentation of the file, or of particular
>> functions.
>
> I don't think that would be sufficient unless it were disabled for
> __restore_processor_state() and all the functions it calls (and the
> functions they call, etc), which wouldn't necessarily be
> straightforward.
>
>> Or we could call kasan_unpoison_shadow() on the stack range
>> before switching to it.
>
> I tried that already, but it hung because restore_processor_state()
> hadn't been called yet (the catch-22 I mentioned aboved).

Ah, I see, we just can't execute normal C code at that point...

Re: [PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume

[Josh Poimboeuf]

On Thu, Dec 01, 2016 at 06:27:31PM +0100, Dmitry Vyukov wrote:
> On Thu, Dec 1, 2016 at 6:13 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > On Thu, Dec 01, 2016 at 05:51:52PM +0100, Dmitry Vyukov wrote:
> >> On Thu, Dec 1, 2016 at 5:45 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> >> > On Thu, Dec 01, 2016 at 08:58:21AM -0600, Josh Poimboeuf wrote:
> >> >> On Thu, Dec 01, 2016 at 12:05:34PM +0300, Andrey Ryabinin wrote:
> >> >> >
> >> >> >
> >> >> > On 12/01/2016 02:10 AM, Josh Poimboeuf wrote:
> >> >> > > Resuming from a suspend operation is showing a KASAN false positive
> >> >> > > warning:
> >> >> > >
> >> >> >
> >> >> > > KASAN instrumentation poisons the stack when entering a function and
> >> >> > > unpoisons it when exiting the function.  However, in the suspend path,
> >> >> > > some functions never return, so their stack never gets unpoisoned,
> >> >> > > resulting in stale KASAN shadow data which can cause false positive
> >> >> > > warnings like the one above.
> >> >> > >
> >> >> > > Reported-by: Scott Bauer <scott.bauer@intel.com>
> >> >> > > Tested-by: Scott Bauer <scott.bauer@intel.com>
> >> >> > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> >> >> > > ---
> >> >> > >  arch/x86/kernel/acpi/sleep.c | 3 +++
> >> >> > >  include/linux/kasan.h        | 7 +++++++
> >> >> > >  2 files changed, 10 insertions(+)
> >> >> > >
> >> >> > > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
> >> >> > > index 4858733..62bd046 100644
> >> >> > > --- a/arch/x86/kernel/acpi/sleep.c
> >> >> > > +++ b/arch/x86/kernel/acpi/sleep.c
> >> >> > > @@ -115,6 +115,9 @@ int x86_acpi_suspend_lowlevel(void)
> >> >> > >   pause_graph_tracing();
> >> >> > >   do_suspend_lowlevel();
> >> >> > >   unpause_graph_tracing();
> >> >> > > +
> >> >> > > + kasan_unpoison_stack_below_sp();
> >> >> > > +
> >> >> >
> >> >> > I think this might be too late. We may hit stale poison in the first C function called
> >> >> > after resume (restore_processor_state()). Thus the shadow must be unpoisoned prior such call,
> >> >> > i.e. somewhere in do_suspend_lowlevel() after .Lresume_point.
> >> >>
> >> >> Yeah, I think you're right.  Will spin a v2.
> >> >
> >> > So I tried calling kasan_unpoison_task_stack_below() from
> >> > do_suspend_lowlevel(), but it hung on the resume.  Presumably because
> >> > restore_processor_state() does some important setup which would be
> >> > needed before calling into kasan_unpoison_task_stack_below().  For
> >> > example, setting up the gs register.  So it's a bit of a catch-22.
> >> >
> >> > It could probably be fixed properly by rewriting do_suspend_lowlevel()
> >> > to call restore_processor_state() with the temporary stack before
> >> > switching to the original stack and doing the unpoison.
> >> >
> >> > (And there are some other issues with do_suspend_lowlevel() and I'd love
> >> > to try taking a scalpel to it.  But I have too many knives in the air
> >> > already to want to try to attempt that right now...)
> >> >
> >> > Unless somebody else wants to take a stab at it, my original patch is
> >> > probably good enough for now, since restore_processor_state() doesn't
> >> > seem to be triggering any KASAN warnings.
> >>
> >> restore_processor_state/__restore_processor_state does not seem to
> >> have any local variables, so KASAN does not do any stack checks there.
> >
> > Actually, looking at the object code, it uses a lot of stack space and
> > has several calls to __asan_report_load*() functions.  Probably due to
> > inlining of other functions which have stack variables.
> 
> That can be loads of heap variables (or other non-stack data). KASAN
> will emit these checks for lots of loads, but they don't necessary go
> to stack.

I also see the stack poisoning instructions:

 54f:   49 c1 ee 03             shr    $0x3,%r14
 553:   4c 01 f0                add    %r14,%rax
 556:   c7 00 f1 f1 f1 f1       movl   $0xf1f1f1f1,(%rax)
 55c:   c7 40 04 00 00 f4 f4    movl   $0xf4f40000,0x4(%rax)
 563:   c7 40 08 f3 f3 f3 f3    movl   $0xf3f3f3f3,0x8(%rax)

> >> We could disable KASAN instrumentation of the file, or of particular
> >> functions.
> >
> > I don't think that would be sufficient unless it were disabled for
> > __restore_processor_state() and all the functions it calls (and the
> > functions they call, etc), which wouldn't necessarily be
> > straightforward.
> >
> >> Or we could call kasan_unpoison_shadow() on the stack range
> >> before switching to it.
> >
> > I tried that already, but it hung because restore_processor_state()
> > hadn't been called yet (the catch-22 I mentioned aboved).
> 
> Ah, I see, we just can't execute normal C code at that point...

Right.

-- 
Josh

Re: [PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume

[Dmitry Vyukov]

On Thu, Dec 1, 2016 at 6:34 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
>> >> >> >
>> >> >> > On 12/01/2016 02:10 AM, Josh Poimboeuf wrote:
>> >> >> > > Resuming from a suspend operation is showing a KASAN false positive
>> >> >> > > warning:
>> >> >> > >
>> >> >> >
>> >> >> > > KASAN instrumentation poisons the stack when entering a function and
>> >> >> > > unpoisons it when exiting the function.  However, in the suspend path,
>> >> >> > > some functions never return, so their stack never gets unpoisoned,
>> >> >> > > resulting in stale KASAN shadow data which can cause false positive
>> >> >> > > warnings like the one above.
>> >> >> > >
>> >> >> > > Reported-by: Scott Bauer <scott.bauer@intel.com>
>> >> >> > > Tested-by: Scott Bauer <scott.bauer@intel.com>
>> >> >> > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
>> >> >> > > ---
>> >> >> > >  arch/x86/kernel/acpi/sleep.c | 3 +++
>> >> >> > >  include/linux/kasan.h        | 7 +++++++
>> >> >> > >  2 files changed, 10 insertions(+)
>> >> >> > >
>> >> >> > > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
>> >> >> > > index 4858733..62bd046 100644
>> >> >> > > --- a/arch/x86/kernel/acpi/sleep.c
>> >> >> > > +++ b/arch/x86/kernel/acpi/sleep.c
>> >> >> > > @@ -115,6 +115,9 @@ int x86_acpi_suspend_lowlevel(void)
>> >> >> > >   pause_graph_tracing();
>> >> >> > >   do_suspend_lowlevel();
>> >> >> > >   unpause_graph_tracing();
>> >> >> > > +
>> >> >> > > + kasan_unpoison_stack_below_sp();
>> >> >> > > +
>> >> >> >
>> >> >> > I think this might be too late. We may hit stale poison in the first C function called
>> >> >> > after resume (restore_processor_state()). Thus the shadow must be unpoisoned prior such call,
>> >> >> > i.e. somewhere in do_suspend_lowlevel() after .Lresume_point.
>> >> >>
>> >> >> Yeah, I think you're right.  Will spin a v2.
>> >> >
>> >> > So I tried calling kasan_unpoison_task_stack_below() from
>> >> > do_suspend_lowlevel(), but it hung on the resume.  Presumably because
>> >> > restore_processor_state() does some important setup which would be
>> >> > needed before calling into kasan_unpoison_task_stack_below().  For
>> >> > example, setting up the gs register.  So it's a bit of a catch-22.
>> >> >
>> >> > It could probably be fixed properly by rewriting do_suspend_lowlevel()
>> >> > to call restore_processor_state() with the temporary stack before
>> >> > switching to the original stack and doing the unpoison.
>> >> >
>> >> > (And there are some other issues with do_suspend_lowlevel() and I'd love
>> >> > to try taking a scalpel to it.  But I have too many knives in the air
>> >> > already to want to try to attempt that right now...)
>> >> >
>> >> > Unless somebody else wants to take a stab at it, my original patch is
>> >> > probably good enough for now, since restore_processor_state() doesn't
>> >> > seem to be triggering any KASAN warnings.
>> >>
>> >> restore_processor_state/__restore_processor_state does not seem to
>> >> have any local variables, so KASAN does not do any stack checks there.
>> >
>> > Actually, looking at the object code, it uses a lot of stack space and
>> > has several calls to __asan_report_load*() functions.  Probably due to
>> > inlining of other functions which have stack variables.
>>
>> That can be loads of heap variables (or other non-stack data). KASAN
>> will emit these checks for lots of loads, but they don't necessary go
>> to stack.
>
> I also see the stack poisoning instructions:
>
>  54f:   49 c1 ee 03             shr    $0x3,%r14
>  553:   4c 01 f0                add    %r14,%rax
>  556:   c7 00 f1 f1 f1 f1       movl   $0xf1f1f1f1,(%rax)
>  55c:   c7 40 04 00 00 f4 f4    movl   $0xf4f40000,0x4(%rax)
>  563:   c7 40 08 f3 f3 f3 f3    movl   $0xf3f3f3f3,0x8(%rax)

OK, then we are in trouble potentially.
It may work as long as as the stack region that is used for local vars
in restore_processor_state() does not contain any stale poisoning. But
it can break at any moment.

Have you tried kasan_unpoison_task_stack_below() or kasan_unpoison_shadow()?
I can see how kasan_unpoison_task_stack_below() can hang (it at least
uses current). But kasan_unpoison_shadow() is quite trivial, it
computes shadow address with simple math and writes zeroes there.


>> >> We could disable KASAN instrumentation of the file, or of particular
>> >> functions.
>> >
>> > I don't think that would be sufficient unless it were disabled for
>> > __restore_processor_state() and all the functions it calls (and the
>> > functions they call, etc), which wouldn't necessarily be
>> > straightforward.
>> >
>> >> Or we could call kasan_unpoison_shadow() on the stack range
>> >> before switching to it.
>> >
>> > I tried that already, but it hung because restore_processor_state()
>> > hadn't been called yet (the catch-22 I mentioned aboved).
>>
>> Ah, I see, we just can't execute normal C code at that point...
>
> Right.
>
> --
> Josh
>
> --
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Re: [PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume

[Josh Poimboeuf]

On Thu, Dec 01, 2016 at 06:47:07PM +0100, Dmitry Vyukov wrote:
> On Thu, Dec 1, 2016 at 6:34 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> >> >> >> >
> >> >> >> > On 12/01/2016 02:10 AM, Josh Poimboeuf wrote:
> >> >> >> > > Resuming from a suspend operation is showing a KASAN false positive
> >> >> >> > > warning:
> >> >> >> > >
> >> >> >> >
> >> >> >> > > KASAN instrumentation poisons the stack when entering a function and
> >> >> >> > > unpoisons it when exiting the function.  However, in the suspend path,
> >> >> >> > > some functions never return, so their stack never gets unpoisoned,
> >> >> >> > > resulting in stale KASAN shadow data which can cause false positive
> >> >> >> > > warnings like the one above.
> >> >> >> > >
> >> >> >> > > Reported-by: Scott Bauer <scott.bauer@intel.com>
> >> >> >> > > Tested-by: Scott Bauer <scott.bauer@intel.com>
> >> >> >> > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> >> >> >> > > ---
> >> >> >> > >  arch/x86/kernel/acpi/sleep.c | 3 +++
> >> >> >> > >  include/linux/kasan.h        | 7 +++++++
> >> >> >> > >  2 files changed, 10 insertions(+)
> >> >> >> > >
> >> >> >> > > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
> >> >> >> > > index 4858733..62bd046 100644
> >> >> >> > > --- a/arch/x86/kernel/acpi/sleep.c
> >> >> >> > > +++ b/arch/x86/kernel/acpi/sleep.c
> >> >> >> > > @@ -115,6 +115,9 @@ int x86_acpi_suspend_lowlevel(void)
> >> >> >> > >   pause_graph_tracing();
> >> >> >> > >   do_suspend_lowlevel();
> >> >> >> > >   unpause_graph_tracing();
> >> >> >> > > +
> >> >> >> > > + kasan_unpoison_stack_below_sp();
> >> >> >> > > +
> >> >> >> >
> >> >> >> > I think this might be too late. We may hit stale poison in the first C function called
> >> >> >> > after resume (restore_processor_state()). Thus the shadow must be unpoisoned prior such call,
> >> >> >> > i.e. somewhere in do_suspend_lowlevel() after .Lresume_point.
> >> >> >>
> >> >> >> Yeah, I think you're right.  Will spin a v2.
> >> >> >
> >> >> > So I tried calling kasan_unpoison_task_stack_below() from
> >> >> > do_suspend_lowlevel(), but it hung on the resume.  Presumably because
> >> >> > restore_processor_state() does some important setup which would be
> >> >> > needed before calling into kasan_unpoison_task_stack_below().  For
> >> >> > example, setting up the gs register.  So it's a bit of a catch-22.
> >> >> >
> >> >> > It could probably be fixed properly by rewriting do_suspend_lowlevel()
> >> >> > to call restore_processor_state() with the temporary stack before
> >> >> > switching to the original stack and doing the unpoison.
> >> >> >
> >> >> > (And there are some other issues with do_suspend_lowlevel() and I'd love
> >> >> > to try taking a scalpel to it.  But I have too many knives in the air
> >> >> > already to want to try to attempt that right now...)
> >> >> >
> >> >> > Unless somebody else wants to take a stab at it, my original patch is
> >> >> > probably good enough for now, since restore_processor_state() doesn't
> >> >> > seem to be triggering any KASAN warnings.
> >> >>
> >> >> restore_processor_state/__restore_processor_state does not seem to
> >> >> have any local variables, so KASAN does not do any stack checks there.
> >> >
> >> > Actually, looking at the object code, it uses a lot of stack space and
> >> > has several calls to __asan_report_load*() functions.  Probably due to
> >> > inlining of other functions which have stack variables.
> >>
> >> That can be loads of heap variables (or other non-stack data). KASAN
> >> will emit these checks for lots of loads, but they don't necessary go
> >> to stack.
> >
> > I also see the stack poisoning instructions:
> >
> >  54f:   49 c1 ee 03             shr    $0x3,%r14
> >  553:   4c 01 f0                add    %r14,%rax
> >  556:   c7 00 f1 f1 f1 f1       movl   $0xf1f1f1f1,(%rax)
> >  55c:   c7 40 04 00 00 f4 f4    movl   $0xf4f40000,0x4(%rax)
> >  563:   c7 40 08 f3 f3 f3 f3    movl   $0xf3f3f3f3,0x8(%rax)
> 
> OK, then we are in trouble potentially.
> It may work as long as as the stack region that is used for local vars
> in restore_processor_state() does not contain any stale poisoning. But
> it can break at any moment.
> 
> Have you tried kasan_unpoison_task_stack_below() or kasan_unpoison_shadow()?
> I can see how kasan_unpoison_task_stack_below() can hang (it at least
> uses current). But kasan_unpoison_shadow() is quite trivial, it
> computes shadow address with simple math and writes zeroes there.

Good idea, I'll give kasan_unpoison_shadow() a shot.

-- 
Josh

[PATCH v2] x86/suspend: fix false positive KASAN warning on suspend/resume

[Josh Poimboeuf]

Resuming from a suspend operation is showing a KASAN false positive
warning:

  BUG: KASAN: stack-out-of-bounds in unwind_get_return_address+0x11d/0x130 at addr ffff8803867d7878
  Read of size 8 by task pm-suspend/7774
  page:ffffea000e19f5c0 count:0 mapcount:0 mapping:          (null) index:0x0
  flags: 0x2ffff0000000000()
  page dumped because: kasan: bad access detected
  CPU: 0 PID: 7774 Comm: pm-suspend Tainted: G    B           4.9.0-rc7+ #8
  Hardware name: Gigabyte Technology Co., Ltd. Z170X-UD5/Z170X-UD5-CF, BIOS F5 03/07/2016
  Call Trace:
    dump_stack+0x63/0x82
    kasan_report_error+0x4b4/0x4e0
    ? acpi_hw_read_port+0xd0/0x1ea
    ? kfree_const+0x22/0x30
    ? acpi_hw_validate_io_request+0x1a6/0x1a6
    __asan_report_load8_noabort+0x61/0x70
    ? unwind_get_return_address+0x11d/0x130
    unwind_get_return_address+0x11d/0x130
    ? unwind_next_frame+0x97/0xf0
    __save_stack_trace+0x92/0x100
    save_stack_trace+0x1b/0x20
    save_stack+0x46/0xd0
    ? save_stack_trace+0x1b/0x20
    ? save_stack+0x46/0xd0
    ? kasan_kmalloc+0xad/0xe0
    ? kasan_slab_alloc+0x12/0x20
    ? acpi_hw_read+0x2b6/0x3aa
    ? acpi_hw_validate_register+0x20b/0x20b
    ? acpi_hw_write_port+0x72/0xc7
    ? acpi_hw_write+0x11f/0x15f
    ? acpi_hw_read_multiple+0x19f/0x19f
    ? memcpy+0x45/0x50
    ? acpi_hw_write_port+0x72/0xc7
    ? acpi_hw_write+0x11f/0x15f
    ? acpi_hw_read_multiple+0x19f/0x19f
    ? kasan_unpoison_shadow+0x36/0x50
    kasan_kmalloc+0xad/0xe0
    kasan_slab_alloc+0x12/0x20
    kmem_cache_alloc_trace+0xbc/0x1e0
    ? acpi_get_sleep_type_data+0x9a/0x578
    acpi_get_sleep_type_data+0x9a/0x578
    acpi_hw_legacy_wake_prep+0x88/0x22c
    ? acpi_hw_legacy_sleep+0x3c7/0x3c7
    ? acpi_write_bit_register+0x28d/0x2d3
    ? acpi_read_bit_register+0x19b/0x19b
    acpi_hw_sleep_dispatch+0xb5/0xba
    acpi_leave_sleep_state_prep+0x17/0x19
    acpi_suspend_enter+0x154/0x1e0
    ? trace_suspend_resume+0xe8/0xe8
    suspend_devices_and_enter+0xb09/0xdb0
    ? printk+0xa8/0xd8
    ? arch_suspend_enable_irqs+0x20/0x20
    ? try_to_freeze_tasks+0x295/0x600
    pm_suspend+0x6c9/0x780
    ? finish_wait+0x1f0/0x1f0
    ? suspend_devices_and_enter+0xdb0/0xdb0
    state_store+0xa2/0x120
    ? kobj_attr_show+0x60/0x60
    kobj_attr_store+0x36/0x70
    sysfs_kf_write+0x131/0x200
    kernfs_fop_write+0x295/0x3f0
    __vfs_write+0xef/0x760
    ? handle_mm_fault+0x1346/0x35e0
    ? do_iter_readv_writev+0x660/0x660
    ? __pmd_alloc+0x310/0x310
    ? do_lock_file_wait+0x1e0/0x1e0
    ? apparmor_file_permission+0x18/0x20
    ? security_file_permission+0x73/0x1c0
    ? rw_verify_area+0xbd/0x2b0
    vfs_write+0x149/0x4a0
    SyS_write+0xd9/0x1c0
    ? SyS_read+0x1c0/0x1c0
    entry_SYSCALL_64_fastpath+0x1e/0xad
  Memory state around the buggy address:
   ffff8803867d7700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
   ffff8803867d7780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  >ffff8803867d7800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f4
                                                                  ^
   ffff8803867d7880: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
   ffff8803867d7900: 00 00 00 f1 f1 f1 f1 04 f4 f4 f4 f3 f3 f3 f3 00

KASAN instrumentation poisons the stack when entering a function and
unpoisons it when exiting the function.  However, in the suspend path,
some functions never return, so their stack never gets unpoisoned,
resulting in stale KASAN shadow data which can cause later false
positive warnings like the one above.

Reported-by: Scott Bauer <scott.bauer@intel.com>
Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 arch/x86/kernel/acpi/wakeup_64.S | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
index 169963f..1df9b75 100644
--- a/arch/x86/kernel/acpi/wakeup_64.S
+++ b/arch/x86/kernel/acpi/wakeup_64.S
@@ -109,6 +109,22 @@ ENTRY(do_suspend_lowlevel)
 	movq	pt_regs_r14(%rax), %r14
 	movq	pt_regs_r15(%rax), %r15
 
+#ifdef CONFIG_KASAN
+	/*
+	 * The suspend path may have poisoned some areas deeper in the stack,
+	 * which we now need to unpoison.
+	 *
+	 * We can't call kasan_unpoison_task_stack_below() because it uses %gs
+	 * for 'current', which hasn't been set up yet.  Instead, calculate the
+	 * stack range manually and call kasan_unpoison_shadow().
+	 */
+	movq	%rsp, %rdi
+	andq	$CURRENT_MASK, %rdi
+	movq	%rsp, %rsi
+	xorq	%rdi, %rsi
+	call	kasan_unpoison_shadow
+#endif
+
 	xorl	%eax, %eax
 	addq	$8, %rsp
 	FRAME_END
-- 
2.7.4

Re: [PATCH v2] x86/suspend: fix false positive KASAN warning on suspend/resume

[Dmitry Vyukov]

On Thu, Dec 1, 2016 at 9:31 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> Resuming from a suspend operation is showing a KASAN false positive
> warning:
>
>   BUG: KASAN: stack-out-of-bounds in unwind_get_return_address+0x11d/0x130 at addr ffff8803867d7878
>   Read of size 8 by task pm-suspend/7774
>   page:ffffea000e19f5c0 count:0 mapcount:0 mapping:          (null) index:0x0
>   flags: 0x2ffff0000000000()
>   page dumped because: kasan: bad access detected
>   CPU: 0 PID: 7774 Comm: pm-suspend Tainted: G    B           4.9.0-rc7+ #8
>   Hardware name: Gigabyte Technology Co., Ltd. Z170X-UD5/Z170X-UD5-CF, BIOS F5 03/07/2016
>   Call Trace:
>     dump_stack+0x63/0x82
>     kasan_report_error+0x4b4/0x4e0
>     ? acpi_hw_read_port+0xd0/0x1ea
>     ? kfree_const+0x22/0x30
>     ? acpi_hw_validate_io_request+0x1a6/0x1a6
>     __asan_report_load8_noabort+0x61/0x70
>     ? unwind_get_return_address+0x11d/0x130
>     unwind_get_return_address+0x11d/0x130
>     ? unwind_next_frame+0x97/0xf0
>     __save_stack_trace+0x92/0x100
>     save_stack_trace+0x1b/0x20
>     save_stack+0x46/0xd0
>     ? save_stack_trace+0x1b/0x20
>     ? save_stack+0x46/0xd0
>     ? kasan_kmalloc+0xad/0xe0
>     ? kasan_slab_alloc+0x12/0x20
>     ? acpi_hw_read+0x2b6/0x3aa
>     ? acpi_hw_validate_register+0x20b/0x20b
>     ? acpi_hw_write_port+0x72/0xc7
>     ? acpi_hw_write+0x11f/0x15f
>     ? acpi_hw_read_multiple+0x19f/0x19f
>     ? memcpy+0x45/0x50
>     ? acpi_hw_write_port+0x72/0xc7
>     ? acpi_hw_write+0x11f/0x15f
>     ? acpi_hw_read_multiple+0x19f/0x19f
>     ? kasan_unpoison_shadow+0x36/0x50
>     kasan_kmalloc+0xad/0xe0
>     kasan_slab_alloc+0x12/0x20
>     kmem_cache_alloc_trace+0xbc/0x1e0
>     ? acpi_get_sleep_type_data+0x9a/0x578
>     acpi_get_sleep_type_data+0x9a/0x578
>     acpi_hw_legacy_wake_prep+0x88/0x22c
>     ? acpi_hw_legacy_sleep+0x3c7/0x3c7
>     ? acpi_write_bit_register+0x28d/0x2d3
>     ? acpi_read_bit_register+0x19b/0x19b
>     acpi_hw_sleep_dispatch+0xb5/0xba
>     acpi_leave_sleep_state_prep+0x17/0x19
>     acpi_suspend_enter+0x154/0x1e0
>     ? trace_suspend_resume+0xe8/0xe8
>     suspend_devices_and_enter+0xb09/0xdb0
>     ? printk+0xa8/0xd8
>     ? arch_suspend_enable_irqs+0x20/0x20
>     ? try_to_freeze_tasks+0x295/0x600
>     pm_suspend+0x6c9/0x780
>     ? finish_wait+0x1f0/0x1f0
>     ? suspend_devices_and_enter+0xdb0/0xdb0
>     state_store+0xa2/0x120
>     ? kobj_attr_show+0x60/0x60
>     kobj_attr_store+0x36/0x70
>     sysfs_kf_write+0x131/0x200
>     kernfs_fop_write+0x295/0x3f0
>     __vfs_write+0xef/0x760
>     ? handle_mm_fault+0x1346/0x35e0
>     ? do_iter_readv_writev+0x660/0x660
>     ? __pmd_alloc+0x310/0x310
>     ? do_lock_file_wait+0x1e0/0x1e0
>     ? apparmor_file_permission+0x18/0x20
>     ? security_file_permission+0x73/0x1c0
>     ? rw_verify_area+0xbd/0x2b0
>     vfs_write+0x149/0x4a0
>     SyS_write+0xd9/0x1c0
>     ? SyS_read+0x1c0/0x1c0
>     entry_SYSCALL_64_fastpath+0x1e/0xad
>   Memory state around the buggy address:
>    ffff8803867d7700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>    ffff8803867d7780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   >ffff8803867d7800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f4
>                                                                   ^
>    ffff8803867d7880: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
>    ffff8803867d7900: 00 00 00 f1 f1 f1 f1 04 f4 f4 f4 f3 f3 f3 f3 00
>
> KASAN instrumentation poisons the stack when entering a function and
> unpoisons it when exiting the function.  However, in the suspend path,
> some functions never return, so their stack never gets unpoisoned,
> resulting in stale KASAN shadow data which can cause later false
> positive warnings like the one above.
>
> Reported-by: Scott Bauer <scott.bauer@intel.com>
> Suggested-by: Dmitry Vyukov <dvyukov@google.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> ---
>  arch/x86/kernel/acpi/wakeup_64.S | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
> index 169963f..1df9b75 100644
> --- a/arch/x86/kernel/acpi/wakeup_64.S
> +++ b/arch/x86/kernel/acpi/wakeup_64.S
> @@ -109,6 +109,22 @@ ENTRY(do_suspend_lowlevel)
>         movq    pt_regs_r14(%rax), %r14
>         movq    pt_regs_r15(%rax), %r15
>
> +#ifdef CONFIG_KASAN
> +       /*
> +        * The suspend path may have poisoned some areas deeper in the stack,
> +        * which we now need to unpoison.
> +        *
> +        * We can't call kasan_unpoison_task_stack_below() because it uses %gs
> +        * for 'current', which hasn't been set up yet.  Instead, calculate the
> +        * stack range manually and call kasan_unpoison_shadow().
> +        */
> +       movq    %rsp, %rdi
> +       andq    $CURRENT_MASK, %rdi
> +       movq    %rsp, %rsi
> +       xorq    %rdi, %rsi
> +       call    kasan_unpoison_shadow
> +#endif
> +
>         xorl    %eax, %eax
>         addq    $8, %rsp
>         FRAME_END


Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

Thanks!

Re: [PATCH v2] x86/suspend: fix false positive KASAN warning on suspend/resume

[Pavel Machek]

[-- Attachment #1: Type: text/plain, Size: 1963 bytes --]

Hi!

> Resuming from a suspend operation is showing a KASAN false positive
> warning:

> KASAN instrumentation poisons the stack when entering a function and
> unpoisons it when exiting the function.  However, in the suspend path,
> some functions never return, so their stack never gets unpoisoned,
> resulting in stale KASAN shadow data which can cause later false
> positive warnings like the one above.
> 
> Reported-by: Scott Bauer <scott.bauer@intel.com>
> Suggested-by: Dmitry Vyukov <dvyukov@google.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>

Acked-by: Pavel Machek <pavel@ucw.cz>

> ---
>  arch/x86/kernel/acpi/wakeup_64.S | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
> index 169963f..1df9b75 100644
> --- a/arch/x86/kernel/acpi/wakeup_64.S
> +++ b/arch/x86/kernel/acpi/wakeup_64.S
> @@ -109,6 +109,22 @@ ENTRY(do_suspend_lowlevel)
>  	movq	pt_regs_r14(%rax), %r14
>  	movq	pt_regs_r15(%rax), %r15
>  
> +#ifdef CONFIG_KASAN
> +	/*
> +	 * The suspend path may have poisoned some areas deeper in the stack,
> +	 * which we now need to unpoison.
> +	 *
> +	 * We can't call kasan_unpoison_task_stack_below() because it uses %gs
> +	 * for 'current', which hasn't been set up yet.  Instead, calculate the
> +	 * stack range manually and call kasan_unpoison_shadow().
> +	 */
> +	movq	%rsp, %rdi
> +	andq	$CURRENT_MASK, %rdi
> +	movq	%rsp, %rsi
> +	xorq	%rdi, %rsi
> +	call	kasan_unpoison_shadow
> +#endif

Well... you may want to add note to kasan_unpoison_shadow()

/*
* This is called by early resume code, with cpu not yer properly
* resumed. In particular, %gs may not be set up, and thus current
* is not available.
*/

Thanks,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

Re: [PATCH v2] x86/suspend: fix false positive KASAN warning on suspend/resume

[Andrey Ryabinin]

On 12/01/2016 11:31 PM, Josh Poimboeuf wrote:

>  arch/x86/kernel/acpi/wakeup_64.S | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
> index 169963f..1df9b75 100644
> --- a/arch/x86/kernel/acpi/wakeup_64.S
> +++ b/arch/x86/kernel/acpi/wakeup_64.S
> @@ -109,6 +109,22 @@ ENTRY(do_suspend_lowlevel)
>  	movq	pt_regs_r14(%rax), %r14
>  	movq	pt_regs_r15(%rax), %r15
>  
> +#ifdef CONFIG_KASAN
> +	/*
> +	 * The suspend path may have poisoned some areas deeper in the stack,
> +	 * which we now need to unpoison.
> +	 *
> +	 * We can't call kasan_unpoison_task_stack_below() because it uses %gs
> +	 * for 'current', which hasn't been set up yet.  Instead, calculate the
> +	 * stack range manually and call kasan_unpoison_shadow().
> +	 */
> +	movq	%rsp, %rdi
> +	andq	$CURRENT_MASK, %rdi
> +	movq	%rsp, %rsi
> +	xorq	%rdi, %rsi
> +	call	kasan_unpoison_shadow
> +#endif
> +

Looks good, but in fact we can use kasan_unpoison_task_stack_below(). We just need to change it a little:

diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 70c0097..e779236 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -80,7 +80,9 @@ void kasan_unpoison_task_stack(struct task_struct *task)
 /* Unpoison the stack for the current task beyond a watermark sp value. */
 asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
 {
-       __kasan_unpoison_stack(current, watermark);
+       void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
+
+       kasan_unpoison_shadow(base, watermark - base);
 }


With this we don't have to calculate stack range in assembly.

Re: [PATCH v2] x86/suspend: fix false positive KASAN warning on suspend/resume

[Josh Poimboeuf]

On Fri, Dec 02, 2016 at 04:41:09PM +0300, Andrey Ryabinin wrote:
> 
> 
> On 12/01/2016 11:31 PM, Josh Poimboeuf wrote:
> 
> >  arch/x86/kernel/acpi/wakeup_64.S | 16 ++++++++++++++++
> >  1 file changed, 16 insertions(+)
> > 
> > diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
> > index 169963f..1df9b75 100644
> > --- a/arch/x86/kernel/acpi/wakeup_64.S
> > +++ b/arch/x86/kernel/acpi/wakeup_64.S
> > @@ -109,6 +109,22 @@ ENTRY(do_suspend_lowlevel)
> >  	movq	pt_regs_r14(%rax), %r14
> >  	movq	pt_regs_r15(%rax), %r15
> >  
> > +#ifdef CONFIG_KASAN
> > +	/*
> > +	 * The suspend path may have poisoned some areas deeper in the stack,
> > +	 * which we now need to unpoison.
> > +	 *
> > +	 * We can't call kasan_unpoison_task_stack_below() because it uses %gs
> > +	 * for 'current', which hasn't been set up yet.  Instead, calculate the
> > +	 * stack range manually and call kasan_unpoison_shadow().
> > +	 */
> > +	movq	%rsp, %rdi
> > +	andq	$CURRENT_MASK, %rdi
> > +	movq	%rsp, %rsi
> > +	xorq	%rdi, %rsi
> > +	call	kasan_unpoison_shadow
> > +#endif
> > +
> 
> Looks good, but in fact we can use kasan_unpoison_task_stack_below(). We just need to change it a little:
> 
> diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
> index 70c0097..e779236 100644
> --- a/mm/kasan/kasan.c
> +++ b/mm/kasan/kasan.c
> @@ -80,7 +80,9 @@ void kasan_unpoison_task_stack(struct task_struct *task)
>  /* Unpoison the stack for the current task beyond a watermark sp value. */
>  asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
>  {
> -       __kasan_unpoison_stack(current, watermark);
> +       void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
> +
> +       kasan_unpoison_shadow(base, watermark - base);
>  }
> 
> 
> With this we don't have to calculate stack range in assembly.

That is better indeed, will do a v3.

-- 
Josh

Re: [PATCH v2] x86/suspend: fix false positive KASAN warning on suspend/resume

[Dmitry Vyukov]

On Fri, Dec 2, 2016 at 3:01 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> On Fri, Dec 02, 2016 at 04:41:09PM +0300, Andrey Ryabinin wrote:
>>
>>
>> On 12/01/2016 11:31 PM, Josh Poimboeuf wrote:
>>
>> >  arch/x86/kernel/acpi/wakeup_64.S | 16 ++++++++++++++++
>> >  1 file changed, 16 insertions(+)
>> >
>> > diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
>> > index 169963f..1df9b75 100644
>> > --- a/arch/x86/kernel/acpi/wakeup_64.S
>> > +++ b/arch/x86/kernel/acpi/wakeup_64.S
>> > @@ -109,6 +109,22 @@ ENTRY(do_suspend_lowlevel)
>> >     movq    pt_regs_r14(%rax), %r14
>> >     movq    pt_regs_r15(%rax), %r15
>> >
>> > +#ifdef CONFIG_KASAN
>> > +   /*
>> > +    * The suspend path may have poisoned some areas deeper in the stack,
>> > +    * which we now need to unpoison.
>> > +    *
>> > +    * We can't call kasan_unpoison_task_stack_below() because it uses %gs
>> > +    * for 'current', which hasn't been set up yet.  Instead, calculate the
>> > +    * stack range manually and call kasan_unpoison_shadow().
>> > +    */
>> > +   movq    %rsp, %rdi
>> > +   andq    $CURRENT_MASK, %rdi
>> > +   movq    %rsp, %rsi
>> > +   xorq    %rdi, %rsi
>> > +   call    kasan_unpoison_shadow
>> > +#endif
>> > +
>>
>> Looks good, but in fact we can use kasan_unpoison_task_stack_below(). We just need to change it a little:
>>
>> diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
>> index 70c0097..e779236 100644
>> --- a/mm/kasan/kasan.c
>> +++ b/mm/kasan/kasan.c
>> @@ -80,7 +80,9 @@ void kasan_unpoison_task_stack(struct task_struct *task)
>>  /* Unpoison the stack for the current task beyond a watermark sp value. */
>>  asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
>>  {
>> -       __kasan_unpoison_stack(current, watermark);
>> +       void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
>> +
>> +       kasan_unpoison_shadow(base, watermark - base);
>>  }
>>
>>
>> With this we don't have to calculate stack range in assembly.
>
> That is better indeed, will do a v3.

agree

[PATCH v3] x86/suspend: fix false positive KASAN warning on suspend/resume

[Josh Poimboeuf]

Resuming from a suspend operation is showing a KASAN false positive
warning:

  BUG: KASAN: stack-out-of-bounds in unwind_get_return_address+0x11d/0x130 at addr ffff8803867d7878
  Read of size 8 by task pm-suspend/7774
  page:ffffea000e19f5c0 count:0 mapcount:0 mapping:          (null) index:0x0
  flags: 0x2ffff0000000000()
  page dumped because: kasan: bad access detected
  CPU: 0 PID: 7774 Comm: pm-suspend Tainted: G    B           4.9.0-rc7+ #8
  Hardware name: Gigabyte Technology Co., Ltd. Z170X-UD5/Z170X-UD5-CF, BIOS F5 03/07/2016
  Call Trace:
    dump_stack+0x63/0x82
    kasan_report_error+0x4b4/0x4e0
    ? acpi_hw_read_port+0xd0/0x1ea
    ? kfree_const+0x22/0x30
    ? acpi_hw_validate_io_request+0x1a6/0x1a6
    __asan_report_load8_noabort+0x61/0x70
    ? unwind_get_return_address+0x11d/0x130
    unwind_get_return_address+0x11d/0x130
    ? unwind_next_frame+0x97/0xf0
    __save_stack_trace+0x92/0x100
    save_stack_trace+0x1b/0x20
    save_stack+0x46/0xd0
    ? save_stack_trace+0x1b/0x20
    ? save_stack+0x46/0xd0
    ? kasan_kmalloc+0xad/0xe0
    ? kasan_slab_alloc+0x12/0x20
    ? acpi_hw_read+0x2b6/0x3aa
    ? acpi_hw_validate_register+0x20b/0x20b
    ? acpi_hw_write_port+0x72/0xc7
    ? acpi_hw_write+0x11f/0x15f
    ? acpi_hw_read_multiple+0x19f/0x19f
    ? memcpy+0x45/0x50
    ? acpi_hw_write_port+0x72/0xc7
    ? acpi_hw_write+0x11f/0x15f
    ? acpi_hw_read_multiple+0x19f/0x19f
    ? kasan_unpoison_shadow+0x36/0x50
    kasan_kmalloc+0xad/0xe0
    kasan_slab_alloc+0x12/0x20
    kmem_cache_alloc_trace+0xbc/0x1e0
    ? acpi_get_sleep_type_data+0x9a/0x578
    acpi_get_sleep_type_data+0x9a/0x578
    acpi_hw_legacy_wake_prep+0x88/0x22c
    ? acpi_hw_legacy_sleep+0x3c7/0x3c7
    ? acpi_write_bit_register+0x28d/0x2d3
    ? acpi_read_bit_register+0x19b/0x19b
    acpi_hw_sleep_dispatch+0xb5/0xba
    acpi_leave_sleep_state_prep+0x17/0x19
    acpi_suspend_enter+0x154/0x1e0
    ? trace_suspend_resume+0xe8/0xe8
    suspend_devices_and_enter+0xb09/0xdb0
    ? printk+0xa8/0xd8
    ? arch_suspend_enable_irqs+0x20/0x20
    ? try_to_freeze_tasks+0x295/0x600
    pm_suspend+0x6c9/0x780
    ? finish_wait+0x1f0/0x1f0
    ? suspend_devices_and_enter+0xdb0/0xdb0
    state_store+0xa2/0x120
    ? kobj_attr_show+0x60/0x60
    kobj_attr_store+0x36/0x70
    sysfs_kf_write+0x131/0x200
    kernfs_fop_write+0x295/0x3f0
    __vfs_write+0xef/0x760
    ? handle_mm_fault+0x1346/0x35e0
    ? do_iter_readv_writev+0x660/0x660
    ? __pmd_alloc+0x310/0x310
    ? do_lock_file_wait+0x1e0/0x1e0
    ? apparmor_file_permission+0x18/0x20
    ? security_file_permission+0x73/0x1c0
    ? rw_verify_area+0xbd/0x2b0
    vfs_write+0x149/0x4a0
    SyS_write+0xd9/0x1c0
    ? SyS_read+0x1c0/0x1c0
    entry_SYSCALL_64_fastpath+0x1e/0xad
  Memory state around the buggy address:
   ffff8803867d7700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
   ffff8803867d7780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  >ffff8803867d7800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f4
                                                                  ^
   ffff8803867d7880: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
   ffff8803867d7900: 00 00 00 f1 f1 f1 f1 04 f4 f4 f4 f3 f3 f3 f3 00

KASAN instrumentation poisons the stack when entering a function and
unpoisons it when exiting the function.  However, in the suspend path,
some functions never return, so their stack never gets unpoisoned,
resulting in stale KASAN shadow data which can cause later false
positive warnings like the one above.

Reported-by: Scott Bauer <scott.bauer@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 arch/x86/kernel/acpi/wakeup_64.S | 9 +++++++++
 mm/kasan/kasan.c                 | 9 ++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
index 169963f..50b8ed0 100644
--- a/arch/x86/kernel/acpi/wakeup_64.S
+++ b/arch/x86/kernel/acpi/wakeup_64.S
@@ -109,6 +109,15 @@ ENTRY(do_suspend_lowlevel)
 	movq	pt_regs_r14(%rax), %r14
 	movq	pt_regs_r15(%rax), %r15
 
+#ifdef CONFIG_KASAN
+	/*
+	 * The suspend path may have poisoned some areas deeper in the stack,
+	 * which we now need to unpoison.
+	 */
+	movq	%rsp, %rdi
+	call	kasan_unpoison_task_stack_below
+#endif
+
 	xorl	%eax, %eax
 	addq	$8, %rsp
 	FRAME_END
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 0e9505f..e9d8ba0 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -80,7 +80,14 @@ void kasan_unpoison_task_stack(struct task_struct *task)
 /* Unpoison the stack for the current task beyond a watermark sp value. */
 asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
 {
-	__kasan_unpoison_stack(current, watermark);
+	/*
+	 * Calculate the task stack base address.  Avoid using 'current'
+	 * because this function is called by early resume code which hasn't
+	 * yet set up the percpu register (%gs).
+	 */
+	void *base = (void *)((unsigned long)watermark & CURRENT_MASK);
+
+	kasan_unpoison_shadow(base, watermark - base);
 }
 
 /*
-- 
2.7.4

Re: [PATCH v3] x86/suspend: fix false positive KASAN warning on suspend/resume

[Andrey Ryabinin]

On 12/02/2016 05:42 PM, Josh Poimboeuf wrote:


> diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
> index 0e9505f..e9d8ba0 100644
> --- a/mm/kasan/kasan.c
> +++ b/mm/kasan/kasan.c
> @@ -80,7 +80,14 @@ void kasan_unpoison_task_stack(struct task_struct *task)
>  /* Unpoison the stack for the current task beyond a watermark sp value. */
>  asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
>  {
> -	__kasan_unpoison_stack(current, watermark);
> +	/*
> +	 * Calculate the task stack base address.  Avoid using 'current'
> +	 * because this function is called by early resume code which hasn't
> +	 * yet set up the percpu register (%gs).
> +	 */
> +	void *base = (void *)((unsigned long)watermark & CURRENT_MASK);

CURRENT_MASK is defined only on x86...

> +
> +	kasan_unpoison_shadow(base, watermark - base);
>  }
>  
>  /*
> 

Re: [PATCH v3] x86/suspend: fix false positive KASAN warning on suspend/resume

[Josh Poimboeuf]

On Fri, Dec 02, 2016 at 05:45:18PM +0300, Andrey Ryabinin wrote:
> 
> 
> On 12/02/2016 05:42 PM, Josh Poimboeuf wrote:
> 
> 
> > diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
> > index 0e9505f..e9d8ba0 100644
> > --- a/mm/kasan/kasan.c
> > +++ b/mm/kasan/kasan.c
> > @@ -80,7 +80,14 @@ void kasan_unpoison_task_stack(struct task_struct *task)
> >  /* Unpoison the stack for the current task beyond a watermark sp value. */
> >  asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
> >  {
> > -	__kasan_unpoison_stack(current, watermark);
> > +	/*
> > +	 * Calculate the task stack base address.  Avoid using 'current'
> > +	 * because this function is called by early resume code which hasn't
> > +	 * yet set up the percpu register (%gs).
> > +	 */
> > +	void *base = (void *)((unsigned long)watermark & CURRENT_MASK);
> 
> CURRENT_MASK is defined only on x86...

Oops.  I guess I should have taken your suggested patch verbatim...

Will do a proper multi-arch compile before submitting v4.

-- 
Josh

[PATCH v4] x86/suspend: fix false positive KASAN warning on suspend/resume

[Josh Poimboeuf]

Resuming from a suspend operation is showing a KASAN false positive
warning:

  BUG: KASAN: stack-out-of-bounds in unwind_get_return_address+0x11d/0x130 at addr ffff8803867d7878
  Read of size 8 by task pm-suspend/7774
  page:ffffea000e19f5c0 count:0 mapcount:0 mapping:          (null) index:0x0
  flags: 0x2ffff0000000000()
  page dumped because: kasan: bad access detected
  CPU: 0 PID: 7774 Comm: pm-suspend Tainted: G    B           4.9.0-rc7+ #8
  Hardware name: Gigabyte Technology Co., Ltd. Z170X-UD5/Z170X-UD5-CF, BIOS F5 03/07/2016
  Call Trace:
    dump_stack+0x63/0x82
    kasan_report_error+0x4b4/0x4e0
    ? acpi_hw_read_port+0xd0/0x1ea
    ? kfree_const+0x22/0x30
    ? acpi_hw_validate_io_request+0x1a6/0x1a6
    __asan_report_load8_noabort+0x61/0x70
    ? unwind_get_return_address+0x11d/0x130
    unwind_get_return_address+0x11d/0x130
    ? unwind_next_frame+0x97/0xf0
    __save_stack_trace+0x92/0x100
    save_stack_trace+0x1b/0x20
    save_stack+0x46/0xd0
    ? save_stack_trace+0x1b/0x20
    ? save_stack+0x46/0xd0
    ? kasan_kmalloc+0xad/0xe0
    ? kasan_slab_alloc+0x12/0x20
    ? acpi_hw_read+0x2b6/0x3aa
    ? acpi_hw_validate_register+0x20b/0x20b
    ? acpi_hw_write_port+0x72/0xc7
    ? acpi_hw_write+0x11f/0x15f
    ? acpi_hw_read_multiple+0x19f/0x19f
    ? memcpy+0x45/0x50
    ? acpi_hw_write_port+0x72/0xc7
    ? acpi_hw_write+0x11f/0x15f
    ? acpi_hw_read_multiple+0x19f/0x19f
    ? kasan_unpoison_shadow+0x36/0x50
    kasan_kmalloc+0xad/0xe0
    kasan_slab_alloc+0x12/0x20
    kmem_cache_alloc_trace+0xbc/0x1e0
    ? acpi_get_sleep_type_data+0x9a/0x578
    acpi_get_sleep_type_data+0x9a/0x578
    acpi_hw_legacy_wake_prep+0x88/0x22c
    ? acpi_hw_legacy_sleep+0x3c7/0x3c7
    ? acpi_write_bit_register+0x28d/0x2d3
    ? acpi_read_bit_register+0x19b/0x19b
    acpi_hw_sleep_dispatch+0xb5/0xba
    acpi_leave_sleep_state_prep+0x17/0x19
    acpi_suspend_enter+0x154/0x1e0
    ? trace_suspend_resume+0xe8/0xe8
    suspend_devices_and_enter+0xb09/0xdb0
    ? printk+0xa8/0xd8
    ? arch_suspend_enable_irqs+0x20/0x20
    ? try_to_freeze_tasks+0x295/0x600
    pm_suspend+0x6c9/0x780
    ? finish_wait+0x1f0/0x1f0
    ? suspend_devices_and_enter+0xdb0/0xdb0
    state_store+0xa2/0x120
    ? kobj_attr_show+0x60/0x60
    kobj_attr_store+0x36/0x70
    sysfs_kf_write+0x131/0x200
    kernfs_fop_write+0x295/0x3f0
    __vfs_write+0xef/0x760
    ? handle_mm_fault+0x1346/0x35e0
    ? do_iter_readv_writev+0x660/0x660
    ? __pmd_alloc+0x310/0x310
    ? do_lock_file_wait+0x1e0/0x1e0
    ? apparmor_file_permission+0x18/0x20
    ? security_file_permission+0x73/0x1c0
    ? rw_verify_area+0xbd/0x2b0
    vfs_write+0x149/0x4a0
    SyS_write+0xd9/0x1c0
    ? SyS_read+0x1c0/0x1c0
    entry_SYSCALL_64_fastpath+0x1e/0xad
  Memory state around the buggy address:
   ffff8803867d7700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
   ffff8803867d7780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  >ffff8803867d7800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f4
                                                                  ^
   ffff8803867d7880: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
   ffff8803867d7900: 00 00 00 f1 f1 f1 f1 04 f4 f4 f4 f3 f3 f3 f3 00

KASAN instrumentation poisons the stack when entering a function and
unpoisons it when exiting the function.  However, in the suspend path,
some functions never return, so their stack never gets unpoisoned,
resulting in stale KASAN shadow data which can cause later false
positive warnings like the one above.

Reported-by: Scott Bauer <scott.bauer@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 arch/x86/kernel/acpi/wakeup_64.S | 9 +++++++++
 mm/kasan/kasan.c                 | 9 ++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
index 169963f..50b8ed0 100644
--- a/arch/x86/kernel/acpi/wakeup_64.S
+++ b/arch/x86/kernel/acpi/wakeup_64.S
@@ -109,6 +109,15 @@ ENTRY(do_suspend_lowlevel)
 	movq	pt_regs_r14(%rax), %r14
 	movq	pt_regs_r15(%rax), %r15
 
+#ifdef CONFIG_KASAN
+	/*
+	 * The suspend path may have poisoned some areas deeper in the stack,
+	 * which we now need to unpoison.
+	 */
+	movq	%rsp, %rdi
+	call	kasan_unpoison_task_stack_below
+#endif
+
 	xorl	%eax, %eax
 	addq	$8, %rsp
 	FRAME_END
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 0e9505f..b2a0cff 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -80,7 +80,14 @@ void kasan_unpoison_task_stack(struct task_struct *task)
 /* Unpoison the stack for the current task beyond a watermark sp value. */
 asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
 {
-	__kasan_unpoison_stack(current, watermark);
+	/*
+	 * Calculate the task stack base address.  Avoid using 'current'
+	 * because this function is called by early resume code which hasn't
+	 * yet set up the percpu register (%gs).
+	 */
+	void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
+
+	kasan_unpoison_shadow(base, watermark - base);
 }
 
 /*
-- 
2.7.4

Re: [PATCH v4] x86/suspend: fix false positive KASAN warning on suspend/resume

[Andrey Ryabinin]

On 12/02/2016 08:42 PM, Josh Poimboeuf wrote:
> Resuming from a suspend operation is showing a KASAN false positive
> warning:
> 
>   BUG: KASAN: stack-out-of-bounds in unwind_get_return_address+0x11d/0x130 at addr ffff8803867d7878
>   Read of size 8 by task pm-suspend/7774
>   page:ffffea000e19f5c0 count:0 mapcount:0 mapping:          (null) index:0x0
>   flags: 0x2ffff0000000000()
>   page dumped because: kasan: bad access detected
>   CPU: 0 PID: 7774 Comm: pm-suspend Tainted: G    B           4.9.0-rc7+ #8
>   Hardware name: Gigabyte Technology Co., Ltd. Z170X-UD5/Z170X-UD5-CF, BIOS F5 03/07/2016
>   Call Trace:
>     dump_stack+0x63/0x82
>     kasan_report_error+0x4b4/0x4e0
>     ? acpi_hw_read_port+0xd0/0x1ea
>     ? kfree_const+0x22/0x30
>     ? acpi_hw_validate_io_request+0x1a6/0x1a6
>     __asan_report_load8_noabort+0x61/0x70
>     ? unwind_get_return_address+0x11d/0x130
>     unwind_get_return_address+0x11d/0x130
>     ? unwind_next_frame+0x97/0xf0
>     __save_stack_trace+0x92/0x100
>     save_stack_trace+0x1b/0x20
>     save_stack+0x46/0xd0
>     ? save_stack_trace+0x1b/0x20
>     ? save_stack+0x46/0xd0
>     ? kasan_kmalloc+0xad/0xe0
>     ? kasan_slab_alloc+0x12/0x20
>     ? acpi_hw_read+0x2b6/0x3aa
>     ? acpi_hw_validate_register+0x20b/0x20b
>     ? acpi_hw_write_port+0x72/0xc7
>     ? acpi_hw_write+0x11f/0x15f
>     ? acpi_hw_read_multiple+0x19f/0x19f
>     ? memcpy+0x45/0x50
>     ? acpi_hw_write_port+0x72/0xc7
>     ? acpi_hw_write+0x11f/0x15f
>     ? acpi_hw_read_multiple+0x19f/0x19f
>     ? kasan_unpoison_shadow+0x36/0x50
>     kasan_kmalloc+0xad/0xe0
>     kasan_slab_alloc+0x12/0x20
>     kmem_cache_alloc_trace+0xbc/0x1e0
>     ? acpi_get_sleep_type_data+0x9a/0x578
>     acpi_get_sleep_type_data+0x9a/0x578
>     acpi_hw_legacy_wake_prep+0x88/0x22c
>     ? acpi_hw_legacy_sleep+0x3c7/0x3c7
>     ? acpi_write_bit_register+0x28d/0x2d3
>     ? acpi_read_bit_register+0x19b/0x19b
>     acpi_hw_sleep_dispatch+0xb5/0xba
>     acpi_leave_sleep_state_prep+0x17/0x19
>     acpi_suspend_enter+0x154/0x1e0
>     ? trace_suspend_resume+0xe8/0xe8
>     suspend_devices_and_enter+0xb09/0xdb0
>     ? printk+0xa8/0xd8
>     ? arch_suspend_enable_irqs+0x20/0x20
>     ? try_to_freeze_tasks+0x295/0x600
>     pm_suspend+0x6c9/0x780
>     ? finish_wait+0x1f0/0x1f0
>     ? suspend_devices_and_enter+0xdb0/0xdb0
>     state_store+0xa2/0x120
>     ? kobj_attr_show+0x60/0x60
>     kobj_attr_store+0x36/0x70
>     sysfs_kf_write+0x131/0x200
>     kernfs_fop_write+0x295/0x3f0
>     __vfs_write+0xef/0x760
>     ? handle_mm_fault+0x1346/0x35e0
>     ? do_iter_readv_writev+0x660/0x660
>     ? __pmd_alloc+0x310/0x310
>     ? do_lock_file_wait+0x1e0/0x1e0
>     ? apparmor_file_permission+0x18/0x20
>     ? security_file_permission+0x73/0x1c0
>     ? rw_verify_area+0xbd/0x2b0
>     vfs_write+0x149/0x4a0
>     SyS_write+0xd9/0x1c0
>     ? SyS_read+0x1c0/0x1c0
>     entry_SYSCALL_64_fastpath+0x1e/0xad
>   Memory state around the buggy address:
>    ffff8803867d7700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>    ffff8803867d7780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   >ffff8803867d7800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f4
>                                                                   ^
>    ffff8803867d7880: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
>    ffff8803867d7900: 00 00 00 f1 f1 f1 f1 04 f4 f4 f4 f3 f3 f3 f3 00
> 
> KASAN instrumentation poisons the stack when entering a function and
> unpoisons it when exiting the function.  However, in the suspend path,
> some functions never return, so their stack never gets unpoisoned,
> resulting in stale KASAN shadow data which can cause later false
> positive warnings like the one above.
> 
> Reported-by: Scott Bauer <scott.bauer@intel.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>

Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>

Re: [PATCH v4] x86/suspend: fix false positive KASAN warning on suspend/resume

[Pavel Machek]

[-- Attachment #1: Type: text/plain, Size: 1375 bytes --]

On Fri 2016-12-02 11:42:21, Josh Poimboeuf wrote:
> Resuming from a suspend operation is showing a KASAN false positive
> warning:
> 
> 
> Reported-by: Scott Bauer <scott.bauer@intel.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>

Acked-by: Pavel Machek <pavel@ucw.cz>

> diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
> index 0e9505f..b2a0cff 100644
> --- a/mm/kasan/kasan.c
> +++ b/mm/kasan/kasan.c
> @@ -80,7 +80,14 @@ void kasan_unpoison_task_stack(struct task_struct *task)
>  /* Unpoison the stack for the current task beyond a watermark sp value. */
>  asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
>  {
> -	__kasan_unpoison_stack(current, watermark);
> +	/*
> +	 * Calculate the task stack base address.  Avoid using 'current'
> +	 * because this function is called by early resume code which hasn't
> +	 * yet set up the percpu register (%gs).
> +	 */
> +	void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
> +
> +	kasan_unpoison_shadow(base, watermark - base);
>  }
>  

I know you modified this code to be arch-independend... but is it
really? I guess it is portable enough across architectures that run
kasan today..
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

Re: [PATCH v4] x86/suspend: fix false positive KASAN warning on suspend/resume

[Josh Poimboeuf]

On Fri, Dec 02, 2016 at 10:09:03PM +0100, Pavel Machek wrote:
> On Fri 2016-12-02 11:42:21, Josh Poimboeuf wrote:
> > Resuming from a suspend operation is showing a KASAN false positive
> > warning:
> > 
> > 
> > Reported-by: Scott Bauer <scott.bauer@intel.com>
> > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> 
> Acked-by: Pavel Machek <pavel@ucw.cz>
> 
> > diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
> > index 0e9505f..b2a0cff 100644
> > --- a/mm/kasan/kasan.c
> > +++ b/mm/kasan/kasan.c
> > @@ -80,7 +80,14 @@ void kasan_unpoison_task_stack(struct task_struct *task)
> >  /* Unpoison the stack for the current task beyond a watermark sp value. */
> >  asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
> >  {
> > -	__kasan_unpoison_stack(current, watermark);
> > +	/*
> > +	 * Calculate the task stack base address.  Avoid using 'current'
> > +	 * because this function is called by early resume code which hasn't
> > +	 * yet set up the percpu register (%gs).
> > +	 */
> > +	void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
> > +
> > +	kasan_unpoison_shadow(base, watermark - base);
> >  }
> >  
> 
> I know you modified this code to be arch-independend... but is it
> really? I guess it is portable enough across architectures that run
> kasan today..

Yes, it's arch-independent as far as I know.

All the implementations of alloc_thread_stack_node() in kernel/fork.c
create THREAD_SIZE sized/aligned stacks.

ia64 has its own implementation of alloc_thread_stack_node(), which also
has a THREAD_SIZE sized/aligned stack, with task_struct stored at the
beginning.

For those architectures for which stack grows up, they would need to
call a different helper which unpoisons the stack above the watermark,
but that was also the case before my patch.

-- 
Josh

Re: [PATCH v4] x86/suspend: fix false positive KASAN warning on suspend/resume

[Rafael J. Wysocki]

On Friday, December 02, 2016 11:42:21 AM Josh Poimboeuf wrote:
> Resuming from a suspend operation is showing a KASAN false positive
> warning:
> 
>   BUG: KASAN: stack-out-of-bounds in unwind_get_return_address+0x11d/0x130 at addr ffff8803867d7878
>   Read of size 8 by task pm-suspend/7774
>   page:ffffea000e19f5c0 count:0 mapcount:0 mapping:          (null) index:0x0
>   flags: 0x2ffff0000000000()
>   page dumped because: kasan: bad access detected
>   CPU: 0 PID: 7774 Comm: pm-suspend Tainted: G    B           4.9.0-rc7+ #8
>   Hardware name: Gigabyte Technology Co., Ltd. Z170X-UD5/Z170X-UD5-CF, BIOS F5 03/07/2016
>   Call Trace:
>     dump_stack+0x63/0x82
>     kasan_report_error+0x4b4/0x4e0
>     ? acpi_hw_read_port+0xd0/0x1ea
>     ? kfree_const+0x22/0x30
>     ? acpi_hw_validate_io_request+0x1a6/0x1a6
>     __asan_report_load8_noabort+0x61/0x70
>     ? unwind_get_return_address+0x11d/0x130
>     unwind_get_return_address+0x11d/0x130
>     ? unwind_next_frame+0x97/0xf0
>     __save_stack_trace+0x92/0x100
>     save_stack_trace+0x1b/0x20
>     save_stack+0x46/0xd0
>     ? save_stack_trace+0x1b/0x20
>     ? save_stack+0x46/0xd0
>     ? kasan_kmalloc+0xad/0xe0
>     ? kasan_slab_alloc+0x12/0x20
>     ? acpi_hw_read+0x2b6/0x3aa
>     ? acpi_hw_validate_register+0x20b/0x20b
>     ? acpi_hw_write_port+0x72/0xc7
>     ? acpi_hw_write+0x11f/0x15f
>     ? acpi_hw_read_multiple+0x19f/0x19f
>     ? memcpy+0x45/0x50
>     ? acpi_hw_write_port+0x72/0xc7
>     ? acpi_hw_write+0x11f/0x15f
>     ? acpi_hw_read_multiple+0x19f/0x19f
>     ? kasan_unpoison_shadow+0x36/0x50
>     kasan_kmalloc+0xad/0xe0
>     kasan_slab_alloc+0x12/0x20
>     kmem_cache_alloc_trace+0xbc/0x1e0
>     ? acpi_get_sleep_type_data+0x9a/0x578
>     acpi_get_sleep_type_data+0x9a/0x578
>     acpi_hw_legacy_wake_prep+0x88/0x22c
>     ? acpi_hw_legacy_sleep+0x3c7/0x3c7
>     ? acpi_write_bit_register+0x28d/0x2d3
>     ? acpi_read_bit_register+0x19b/0x19b
>     acpi_hw_sleep_dispatch+0xb5/0xba
>     acpi_leave_sleep_state_prep+0x17/0x19
>     acpi_suspend_enter+0x154/0x1e0
>     ? trace_suspend_resume+0xe8/0xe8
>     suspend_devices_and_enter+0xb09/0xdb0
>     ? printk+0xa8/0xd8
>     ? arch_suspend_enable_irqs+0x20/0x20
>     ? try_to_freeze_tasks+0x295/0x600
>     pm_suspend+0x6c9/0x780
>     ? finish_wait+0x1f0/0x1f0
>     ? suspend_devices_and_enter+0xdb0/0xdb0
>     state_store+0xa2/0x120
>     ? kobj_attr_show+0x60/0x60
>     kobj_attr_store+0x36/0x70
>     sysfs_kf_write+0x131/0x200
>     kernfs_fop_write+0x295/0x3f0
>     __vfs_write+0xef/0x760
>     ? handle_mm_fault+0x1346/0x35e0
>     ? do_iter_readv_writev+0x660/0x660
>     ? __pmd_alloc+0x310/0x310
>     ? do_lock_file_wait+0x1e0/0x1e0
>     ? apparmor_file_permission+0x18/0x20
>     ? security_file_permission+0x73/0x1c0
>     ? rw_verify_area+0xbd/0x2b0
>     vfs_write+0x149/0x4a0
>     SyS_write+0xd9/0x1c0
>     ? SyS_read+0x1c0/0x1c0
>     entry_SYSCALL_64_fastpath+0x1e/0xad
>   Memory state around the buggy address:
>    ffff8803867d7700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>    ffff8803867d7780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   >ffff8803867d7800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f4
>                                                                   ^
>    ffff8803867d7880: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
>    ffff8803867d7900: 00 00 00 f1 f1 f1 f1 04 f4 f4 f4 f3 f3 f3 f3 00
> 
> KASAN instrumentation poisons the stack when entering a function and
> unpoisons it when exiting the function.  However, in the suspend path,
> some functions never return, so their stack never gets unpoisoned,
> resulting in stale KASAN shadow data which can cause later false
> positive warnings like the one above.
> 
> Reported-by: Scott Bauer <scott.bauer@intel.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> ---
>  arch/x86/kernel/acpi/wakeup_64.S | 9 +++++++++
>  mm/kasan/kasan.c                 | 9 ++++++++-
>  2 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
> index 169963f..50b8ed0 100644
> --- a/arch/x86/kernel/acpi/wakeup_64.S
> +++ b/arch/x86/kernel/acpi/wakeup_64.S
> @@ -109,6 +109,15 @@ ENTRY(do_suspend_lowlevel)
>  	movq	pt_regs_r14(%rax), %r14
>  	movq	pt_regs_r15(%rax), %r15
>  
> +#ifdef CONFIG_KASAN
> +	/*
> +	 * The suspend path may have poisoned some areas deeper in the stack,
> +	 * which we now need to unpoison.
> +	 */
> +	movq	%rsp, %rdi
> +	call	kasan_unpoison_task_stack_below
> +#endif
> +
>  	xorl	%eax, %eax
>  	addq	$8, %rsp
>  	FRAME_END
> diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
> index 0e9505f..b2a0cff 100644
> --- a/mm/kasan/kasan.c
> +++ b/mm/kasan/kasan.c
> @@ -80,7 +80,14 @@ void kasan_unpoison_task_stack(struct task_struct *task)
>  /* Unpoison the stack for the current task beyond a watermark sp value. */
>  asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
>  {
> -	__kasan_unpoison_stack(current, watermark);
> +	/*
> +	 * Calculate the task stack base address.  Avoid using 'current'
> +	 * because this function is called by early resume code which hasn't
> +	 * yet set up the percpu register (%gs).
> +	 */
> +	void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
> +
> +	kasan_unpoison_shadow(base, watermark - base);
>  }
>  
>  /*
> 

Applied.

Thanks,
Rafael

Re: [PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume

[Rafael J. Wysocki]

On Thu, Dec 1, 2016 at 12:10 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> Resuming from a suspend operation is showing a KASAN false positive
> warning:
>
>   BUG: KASAN: stack-out-of-bounds in unwind_get_return_address+0x11d/0x130 at addr ffff8803867d7878
>   Read of size 8 by task pm-suspend/7774
>   page:ffffea000e19f5c0 count:0 mapcount:0 mapping:          (null) index:0x0
>   flags: 0x2ffff0000000000()
>   page dumped because: kasan: bad access detected
>   CPU: 0 PID: 7774 Comm: pm-suspend Tainted: G    B           4.9.0-rc7+ #8
>   Hardware name: Gigabyte Technology Co., Ltd. Z170X-UD5/Z170X-UD5-CF, BIOS F5 03/07/2016
>    ffff8803867d7468 ffffffffb4c0d051 ffff8803867d7500 ffff8803867d7878
>    ffff8803867d74f0 ffffffffb45cbe34 ffffffffb4e64136 ffffffffb4510d42
>    ffff8803828c3f4c 0000000000000097 0000000041b58ab3 ffffffffb6192731
>   Call Trace:
>     dump_stack+0x63/0x82
>     kasan_report_error+0x4b4/0x4e0
>     ? acpi_hw_read_port+0xd0/0x1ea
>     ? kfree_const+0x22/0x30
>     ? acpi_hw_validate_io_request+0x1a6/0x1a6
>     __asan_report_load8_noabort+0x61/0x70
>     ? unwind_get_return_address+0x11d/0x130
>     unwind_get_return_address+0x11d/0x130
>     ? unwind_next_frame+0x97/0xf0
>     __save_stack_trace+0x92/0x100
>     save_stack_trace+0x1b/0x20
>     save_stack+0x46/0xd0
>     ? save_stack_trace+0x1b/0x20
>     ? save_stack+0x46/0xd0
>     ? kasan_kmalloc+0xad/0xe0
>     ? kasan_slab_alloc+0x12/0x20
>     ? acpi_hw_read+0x2b6/0x3aa
>     ? acpi_hw_validate_register+0x20b/0x20b
>     ? acpi_hw_write_port+0x72/0xc7
>     ? acpi_hw_write+0x11f/0x15f
>     ? acpi_hw_read_multiple+0x19f/0x19f
>     ? memcpy+0x45/0x50
>     ? acpi_hw_write_port+0x72/0xc7
>     ? acpi_hw_write+0x11f/0x15f
>     ? acpi_hw_read_multiple+0x19f/0x19f
>     ? kasan_unpoison_shadow+0x36/0x50
>     kasan_kmalloc+0xad/0xe0
>     kasan_slab_alloc+0x12/0x20
>     kmem_cache_alloc_trace+0xbc/0x1e0
>     ? acpi_get_sleep_type_data+0x9a/0x578
>     acpi_get_sleep_type_data+0x9a/0x578
>     acpi_hw_legacy_wake_prep+0x88/0x22c
>     ? acpi_hw_legacy_sleep+0x3c7/0x3c7
>     ? acpi_write_bit_register+0x28d/0x2d3
>     ? acpi_read_bit_register+0x19b/0x19b
>     acpi_hw_sleep_dispatch+0xb5/0xba
>     acpi_leave_sleep_state_prep+0x17/0x19
>     acpi_suspend_enter+0x154/0x1e0
>     ? trace_suspend_resume+0xe8/0xe8
>     suspend_devices_and_enter+0xb09/0xdb0
>     ? printk+0xa8/0xd8
>     ? arch_suspend_enable_irqs+0x20/0x20
>     ? try_to_freeze_tasks+0x295/0x600
>     pm_suspend+0x6c9/0x780
>     ? finish_wait+0x1f0/0x1f0
>     ? suspend_devices_and_enter+0xdb0/0xdb0
>     state_store+0xa2/0x120
>     ? kobj_attr_show+0x60/0x60
>     kobj_attr_store+0x36/0x70
>     sysfs_kf_write+0x131/0x200
>     kernfs_fop_write+0x295/0x3f0
>     __vfs_write+0xef/0x760
>     ? handle_mm_fault+0x1346/0x35e0
>     ? do_iter_readv_writev+0x660/0x660
>     ? __pmd_alloc+0x310/0x310
>     ? do_lock_file_wait+0x1e0/0x1e0
>     ? apparmor_file_permission+0x18/0x20
>     ? security_file_permission+0x73/0x1c0
>     ? rw_verify_area+0xbd/0x2b0
>     vfs_write+0x149/0x4a0
>     SyS_write+0xd9/0x1c0
>     ? SyS_read+0x1c0/0x1c0
>     entry_SYSCALL_64_fastpath+0x1e/0xad
>   Memory state around the buggy address:
>    ffff8803867d7700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>    ffff8803867d7780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   >ffff8803867d7800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f4
>                                                                   ^
>    ffff8803867d7880: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
>    ffff8803867d7900: 00 00 00 f1 f1 f1 f1 04 f4 f4 f4 f3 f3 f3 f3 00
>
> KASAN instrumentation poisons the stack when entering a function and
> unpoisons it when exiting the function.  However, in the suspend path,
> some functions never return, so their stack never gets unpoisoned,
> resulting in stale KASAN shadow data which can cause false positive
> warnings like the one above.
>
> Reported-by: Scott Bauer <scott.bauer@intel.com>
> Tested-by: Scott Bauer <scott.bauer@intel.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> ---
>  arch/x86/kernel/acpi/sleep.c | 3 +++
>  include/linux/kasan.h        | 7 +++++++
>  2 files changed, 10 insertions(+)
>
> diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
> index 4858733..62bd046 100644
> --- a/arch/x86/kernel/acpi/sleep.c
> +++ b/arch/x86/kernel/acpi/sleep.c
> @@ -115,6 +115,9 @@ int x86_acpi_suspend_lowlevel(void)
>         pause_graph_tracing();
>         do_suspend_lowlevel();
>         unpause_graph_tracing();
> +
> +       kasan_unpoison_stack_below_sp();
> +
>         return 0;
>  }
>
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 820c0ad..e0945d5 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -45,6 +45,12 @@ void kasan_unpoison_shadow(const void *address, size_t size);
>
>  void kasan_unpoison_task_stack(struct task_struct *task);
>  void kasan_unpoison_stack_above_sp_to(const void *watermark);
> +asmlinkage void kasan_unpoison_task_stack_below(const void *watermark);
> +
> +static inline void kasan_unpoison_stack_below_sp(void)
> +{
> +       kasan_unpoison_task_stack_below(__builtin_frame_address(0));
> +}
>
>  void kasan_alloc_pages(struct page *page, unsigned int order);
>  void kasan_free_pages(struct page *page, unsigned int order);
> @@ -87,6 +93,7 @@ static inline void kasan_unpoison_shadow(const void *address, size_t size) {}
>
>  static inline void kasan_unpoison_task_stack(struct task_struct *task) {}
>  static inline void kasan_unpoison_stack_above_sp_to(const void *watermark) {}
> +static inline void kasan_unpoison_stack_below_sp(void) {}
>
>  static inline void kasan_enable_current(void) {}
>  static inline void kasan_disable_current(void) {}
> --

Looks OK to me.

Whom do you expect to apply this?

Thanks,
Rafael

Re: [PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume

[Josh Poimboeuf]

On Thu, Dec 01, 2016 at 03:04:22PM +0100, Rafael J. Wysocki wrote:
> On Thu, Dec 1, 2016 at 12:10 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > Resuming from a suspend operation is showing a KASAN false positive
> > warning:
> >
> >   BUG: KASAN: stack-out-of-bounds in unwind_get_return_address+0x11d/0x130 at addr ffff8803867d7878
> >   Read of size 8 by task pm-suspend/7774
> >   page:ffffea000e19f5c0 count:0 mapcount:0 mapping:          (null) index:0x0
> >   flags: 0x2ffff0000000000()
> >   page dumped because: kasan: bad access detected
> >   CPU: 0 PID: 7774 Comm: pm-suspend Tainted: G    B           4.9.0-rc7+ #8
> >   Hardware name: Gigabyte Technology Co., Ltd. Z170X-UD5/Z170X-UD5-CF, BIOS F5 03/07/2016
> >    ffff8803867d7468 ffffffffb4c0d051 ffff8803867d7500 ffff8803867d7878
> >    ffff8803867d74f0 ffffffffb45cbe34 ffffffffb4e64136 ffffffffb4510d42
> >    ffff8803828c3f4c 0000000000000097 0000000041b58ab3 ffffffffb6192731
> >   Call Trace:
> >     dump_stack+0x63/0x82
> >     kasan_report_error+0x4b4/0x4e0
> >     ? acpi_hw_read_port+0xd0/0x1ea
> >     ? kfree_const+0x22/0x30
> >     ? acpi_hw_validate_io_request+0x1a6/0x1a6
> >     __asan_report_load8_noabort+0x61/0x70
> >     ? unwind_get_return_address+0x11d/0x130
> >     unwind_get_return_address+0x11d/0x130
> >     ? unwind_next_frame+0x97/0xf0
> >     __save_stack_trace+0x92/0x100
> >     save_stack_trace+0x1b/0x20
> >     save_stack+0x46/0xd0
> >     ? save_stack_trace+0x1b/0x20
> >     ? save_stack+0x46/0xd0
> >     ? kasan_kmalloc+0xad/0xe0
> >     ? kasan_slab_alloc+0x12/0x20
> >     ? acpi_hw_read+0x2b6/0x3aa
> >     ? acpi_hw_validate_register+0x20b/0x20b
> >     ? acpi_hw_write_port+0x72/0xc7
> >     ? acpi_hw_write+0x11f/0x15f
> >     ? acpi_hw_read_multiple+0x19f/0x19f
> >     ? memcpy+0x45/0x50
> >     ? acpi_hw_write_port+0x72/0xc7
> >     ? acpi_hw_write+0x11f/0x15f
> >     ? acpi_hw_read_multiple+0x19f/0x19f
> >     ? kasan_unpoison_shadow+0x36/0x50
> >     kasan_kmalloc+0xad/0xe0
> >     kasan_slab_alloc+0x12/0x20
> >     kmem_cache_alloc_trace+0xbc/0x1e0
> >     ? acpi_get_sleep_type_data+0x9a/0x578
> >     acpi_get_sleep_type_data+0x9a/0x578
> >     acpi_hw_legacy_wake_prep+0x88/0x22c
> >     ? acpi_hw_legacy_sleep+0x3c7/0x3c7
> >     ? acpi_write_bit_register+0x28d/0x2d3
> >     ? acpi_read_bit_register+0x19b/0x19b
> >     acpi_hw_sleep_dispatch+0xb5/0xba
> >     acpi_leave_sleep_state_prep+0x17/0x19
> >     acpi_suspend_enter+0x154/0x1e0
> >     ? trace_suspend_resume+0xe8/0xe8
> >     suspend_devices_and_enter+0xb09/0xdb0
> >     ? printk+0xa8/0xd8
> >     ? arch_suspend_enable_irqs+0x20/0x20
> >     ? try_to_freeze_tasks+0x295/0x600
> >     pm_suspend+0x6c9/0x780
> >     ? finish_wait+0x1f0/0x1f0
> >     ? suspend_devices_and_enter+0xdb0/0xdb0
> >     state_store+0xa2/0x120
> >     ? kobj_attr_show+0x60/0x60
> >     kobj_attr_store+0x36/0x70
> >     sysfs_kf_write+0x131/0x200
> >     kernfs_fop_write+0x295/0x3f0
> >     __vfs_write+0xef/0x760
> >     ? handle_mm_fault+0x1346/0x35e0
> >     ? do_iter_readv_writev+0x660/0x660
> >     ? __pmd_alloc+0x310/0x310
> >     ? do_lock_file_wait+0x1e0/0x1e0
> >     ? apparmor_file_permission+0x18/0x20
> >     ? security_file_permission+0x73/0x1c0
> >     ? rw_verify_area+0xbd/0x2b0
> >     vfs_write+0x149/0x4a0
> >     SyS_write+0xd9/0x1c0
> >     ? SyS_read+0x1c0/0x1c0
> >     entry_SYSCALL_64_fastpath+0x1e/0xad
> >   Memory state around the buggy address:
> >    ffff8803867d7700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >    ffff8803867d7780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >   >ffff8803867d7800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f4
> >                                                                   ^
> >    ffff8803867d7880: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
> >    ffff8803867d7900: 00 00 00 f1 f1 f1 f1 04 f4 f4 f4 f3 f3 f3 f3 00
> >
> > KASAN instrumentation poisons the stack when entering a function and
> > unpoisons it when exiting the function.  However, in the suspend path,
> > some functions never return, so their stack never gets unpoisoned,
> > resulting in stale KASAN shadow data which can cause false positive
> > warnings like the one above.
> >
> > Reported-by: Scott Bauer <scott.bauer@intel.com>
> > Tested-by: Scott Bauer <scott.bauer@intel.com>
> > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> > ---
> >  arch/x86/kernel/acpi/sleep.c | 3 +++
> >  include/linux/kasan.h        | 7 +++++++
> >  2 files changed, 10 insertions(+)
> >
> > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
> > index 4858733..62bd046 100644
> > --- a/arch/x86/kernel/acpi/sleep.c
> > +++ b/arch/x86/kernel/acpi/sleep.c
> > @@ -115,6 +115,9 @@ int x86_acpi_suspend_lowlevel(void)
> >         pause_graph_tracing();
> >         do_suspend_lowlevel();
> >         unpause_graph_tracing();
> > +
> > +       kasan_unpoison_stack_below_sp();
> > +
> >         return 0;
> >  }
> >
> > diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> > index 820c0ad..e0945d5 100644
> > --- a/include/linux/kasan.h
> > +++ b/include/linux/kasan.h
> > @@ -45,6 +45,12 @@ void kasan_unpoison_shadow(const void *address, size_t size);
> >
> >  void kasan_unpoison_task_stack(struct task_struct *task);
> >  void kasan_unpoison_stack_above_sp_to(const void *watermark);
> > +asmlinkage void kasan_unpoison_task_stack_below(const void *watermark);
> > +
> > +static inline void kasan_unpoison_stack_below_sp(void)
> > +{
> > +       kasan_unpoison_task_stack_below(__builtin_frame_address(0));
> > +}
> >
> >  void kasan_alloc_pages(struct page *page, unsigned int order);
> >  void kasan_free_pages(struct page *page, unsigned int order);
> > @@ -87,6 +93,7 @@ static inline void kasan_unpoison_shadow(const void *address, size_t size) {}
> >
> >  static inline void kasan_unpoison_task_stack(struct task_struct *task) {}
> >  static inline void kasan_unpoison_stack_above_sp_to(const void *watermark) {}
> > +static inline void kasan_unpoison_stack_below_sp(void) {}
> >
> >  static inline void kasan_enable_current(void) {}
> >  static inline void kasan_disable_current(void) {}
> > --
> 
> Looks OK to me.
> 
> Whom do you expect to apply this?

Assuming it gets an ack from Andrey, can you take it?  Or would the tip
tree be better?

-- 
Josh

Re: [PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume

[Rafael J. Wysocki]

On Thu, Dec 1, 2016 at 5:53 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> On Thu, Dec 01, 2016 at 03:04:22PM +0100, Rafael J. Wysocki wrote:
>> On Thu, Dec 1, 2016 at 12:10 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
>> > Resuming from a suspend operation is showing a KASAN false positive
>> > warning:
>> >
>> >   BUG: KASAN: stack-out-of-bounds in unwind_get_return_address+0x11d/0x130 at addr ffff8803867d7878
>> >   Read of size 8 by task pm-suspend/7774
>> >   page:ffffea000e19f5c0 count:0 mapcount:0 mapping:          (null) index:0x0
>> >   flags: 0x2ffff0000000000()
>> >   page dumped because: kasan: bad access detected
>> >   CPU: 0 PID: 7774 Comm: pm-suspend Tainted: G    B           4.9.0-rc7+ #8
>> >   Hardware name: Gigabyte Technology Co., Ltd. Z170X-UD5/Z170X-UD5-CF, BIOS F5 03/07/2016
>> >    ffff8803867d7468 ffffffffb4c0d051 ffff8803867d7500 ffff8803867d7878
>> >    ffff8803867d74f0 ffffffffb45cbe34 ffffffffb4e64136 ffffffffb4510d42
>> >    ffff8803828c3f4c 0000000000000097 0000000041b58ab3 ffffffffb6192731
>> >   Call Trace:
>> >     dump_stack+0x63/0x82
>> >     kasan_report_error+0x4b4/0x4e0
>> >     ? acpi_hw_read_port+0xd0/0x1ea
>> >     ? kfree_const+0x22/0x30
>> >     ? acpi_hw_validate_io_request+0x1a6/0x1a6
>> >     __asan_report_load8_noabort+0x61/0x70
>> >     ? unwind_get_return_address+0x11d/0x130
>> >     unwind_get_return_address+0x11d/0x130
>> >     ? unwind_next_frame+0x97/0xf0
>> >     __save_stack_trace+0x92/0x100
>> >     save_stack_trace+0x1b/0x20
>> >     save_stack+0x46/0xd0
>> >     ? save_stack_trace+0x1b/0x20
>> >     ? save_stack+0x46/0xd0
>> >     ? kasan_kmalloc+0xad/0xe0
>> >     ? kasan_slab_alloc+0x12/0x20
>> >     ? acpi_hw_read+0x2b6/0x3aa
>> >     ? acpi_hw_validate_register+0x20b/0x20b
>> >     ? acpi_hw_write_port+0x72/0xc7
>> >     ? acpi_hw_write+0x11f/0x15f
>> >     ? acpi_hw_read_multiple+0x19f/0x19f
>> >     ? memcpy+0x45/0x50
>> >     ? acpi_hw_write_port+0x72/0xc7
>> >     ? acpi_hw_write+0x11f/0x15f
>> >     ? acpi_hw_read_multiple+0x19f/0x19f
>> >     ? kasan_unpoison_shadow+0x36/0x50
>> >     kasan_kmalloc+0xad/0xe0
>> >     kasan_slab_alloc+0x12/0x20
>> >     kmem_cache_alloc_trace+0xbc/0x1e0
>> >     ? acpi_get_sleep_type_data+0x9a/0x578
>> >     acpi_get_sleep_type_data+0x9a/0x578
>> >     acpi_hw_legacy_wake_prep+0x88/0x22c
>> >     ? acpi_hw_legacy_sleep+0x3c7/0x3c7
>> >     ? acpi_write_bit_register+0x28d/0x2d3
>> >     ? acpi_read_bit_register+0x19b/0x19b
>> >     acpi_hw_sleep_dispatch+0xb5/0xba
>> >     acpi_leave_sleep_state_prep+0x17/0x19
>> >     acpi_suspend_enter+0x154/0x1e0
>> >     ? trace_suspend_resume+0xe8/0xe8
>> >     suspend_devices_and_enter+0xb09/0xdb0
>> >     ? printk+0xa8/0xd8
>> >     ? arch_suspend_enable_irqs+0x20/0x20
>> >     ? try_to_freeze_tasks+0x295/0x600
>> >     pm_suspend+0x6c9/0x780
>> >     ? finish_wait+0x1f0/0x1f0
>> >     ? suspend_devices_and_enter+0xdb0/0xdb0
>> >     state_store+0xa2/0x120
>> >     ? kobj_attr_show+0x60/0x60
>> >     kobj_attr_store+0x36/0x70
>> >     sysfs_kf_write+0x131/0x200
>> >     kernfs_fop_write+0x295/0x3f0
>> >     __vfs_write+0xef/0x760
>> >     ? handle_mm_fault+0x1346/0x35e0
>> >     ? do_iter_readv_writev+0x660/0x660
>> >     ? __pmd_alloc+0x310/0x310
>> >     ? do_lock_file_wait+0x1e0/0x1e0
>> >     ? apparmor_file_permission+0x18/0x20
>> >     ? security_file_permission+0x73/0x1c0
>> >     ? rw_verify_area+0xbd/0x2b0
>> >     vfs_write+0x149/0x4a0
>> >     SyS_write+0xd9/0x1c0
>> >     ? SyS_read+0x1c0/0x1c0
>> >     entry_SYSCALL_64_fastpath+0x1e/0xad
>> >   Memory state around the buggy address:
>> >    ffff8803867d7700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>> >    ffff8803867d7780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>> >   >ffff8803867d7800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f4
>> >                                                                   ^
>> >    ffff8803867d7880: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
>> >    ffff8803867d7900: 00 00 00 f1 f1 f1 f1 04 f4 f4 f4 f3 f3 f3 f3 00
>> >
>> > KASAN instrumentation poisons the stack when entering a function and
>> > unpoisons it when exiting the function.  However, in the suspend path,
>> > some functions never return, so their stack never gets unpoisoned,
>> > resulting in stale KASAN shadow data which can cause false positive
>> > warnings like the one above.
>> >
>> > Reported-by: Scott Bauer <scott.bauer@intel.com>
>> > Tested-by: Scott Bauer <scott.bauer@intel.com>
>> > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
>> > ---
>> >  arch/x86/kernel/acpi/sleep.c | 3 +++
>> >  include/linux/kasan.h        | 7 +++++++
>> >  2 files changed, 10 insertions(+)
>> >
>> > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
>> > index 4858733..62bd046 100644
>> > --- a/arch/x86/kernel/acpi/sleep.c
>> > +++ b/arch/x86/kernel/acpi/sleep.c
>> > @@ -115,6 +115,9 @@ int x86_acpi_suspend_lowlevel(void)
>> >         pause_graph_tracing();
>> >         do_suspend_lowlevel();
>> >         unpause_graph_tracing();
>> > +
>> > +       kasan_unpoison_stack_below_sp();
>> > +
>> >         return 0;
>> >  }
>> >
>> > diff --git a/include/linux/kasan.h b/include/linux/kasan.h
>> > index 820c0ad..e0945d5 100644
>> > --- a/include/linux/kasan.h
>> > +++ b/include/linux/kasan.h
>> > @@ -45,6 +45,12 @@ void kasan_unpoison_shadow(const void *address, size_t size);
>> >
>> >  void kasan_unpoison_task_stack(struct task_struct *task);
>> >  void kasan_unpoison_stack_above_sp_to(const void *watermark);
>> > +asmlinkage void kasan_unpoison_task_stack_below(const void *watermark);
>> > +
>> > +static inline void kasan_unpoison_stack_below_sp(void)
>> > +{
>> > +       kasan_unpoison_task_stack_below(__builtin_frame_address(0));
>> > +}
>> >
>> >  void kasan_alloc_pages(struct page *page, unsigned int order);
>> >  void kasan_free_pages(struct page *page, unsigned int order);
>> > @@ -87,6 +93,7 @@ static inline void kasan_unpoison_shadow(const void *address, size_t size) {}
>> >
>> >  static inline void kasan_unpoison_task_stack(struct task_struct *task) {}
>> >  static inline void kasan_unpoison_stack_above_sp_to(const void *watermark) {}
>> > +static inline void kasan_unpoison_stack_below_sp(void) {}
>> >
>> >  static inline void kasan_enable_current(void) {}
>> >  static inline void kasan_disable_current(void) {}
>> > --
>>
>> Looks OK to me.
>>
>> Whom do you expect to apply this?
>
> Assuming it gets an ack from Andrey, can you take it?  Or would the tip
> tree be better?

I can take it unless anyone else wants to take care of it. :-)

Thanks,
Rafael

Re: [PATCH] x86/suspend: fix false positive KASAN warning on suspend/resume

[Ingo Molnar]

* Rafael J. Wysocki <rafael@kernel.org> wrote:

> >> Looks OK to me.
> >>
> >> Whom do you expect to apply this?
> >
> > Assuming it gets an ack from Andrey, can you take it?  Or would the tip
> > tree be better?
> 
> I can take it unless anyone else wants to take care of it. :-)

Please pick up the fixes in this thread.

Thanks!

	Ingo