Re: [PATCH] ACPICA: cleanup method properly on error

From: Vegard Nossum
Date: Wed Jul 27 2016 - 01:38:57 EST

On 07/26/2016 10:28 PM, Moore, Robert wrote:
/* Put the new state at the head of the walk list */

if (Thread)
AcpiDsPushWalkState (WalkState, Thread);

Is there any chance that Thread could be zero?

I'm not sure if this question was for me or not, but that code (modulo
the capitalisation differences) is the reason why I also used 'if
(thread)' in my patch.


-----Original Message-----
From: Devel [mailto:devel-bounces@xxxxxxxxxx] On Behalf Of Moore, Robert
Sent: Tuesday, July 26, 2016 7:40 AM
To: Vegard Nossum <vegard.nossum@xxxxxxxxxx>; Zheng, Lv
<lv.zheng@xxxxxxxxx>; Wysocki, Rafael J <rafael.j.wysocki@xxxxxxxxx>
Cc: linux-acpi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
stable@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx
Subject: Re: [Devel] [PATCH] ACPICA: cleanup method properly on error

We'll look at this.

-----Original Message-----
From: Vegard Nossum [mailto:vegard.nossum@xxxxxxxxxx]
Sent: Friday, July 22, 2016 8:35 AM
To: Moore, Robert <robert.moore@xxxxxxxxx>; Zheng, Lv
<lv.zheng@xxxxxxxxx>; Wysocki, Rafael J <rafael.j.wysocki@xxxxxxxxx>
Cc: linux-acpi@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx; linux-
kernel@xxxxxxxxxxxxxxx; Vegard Nossum <vegard.nossum@xxxxxxxxxx>;
Subject: [PATCH] ACPICA: cleanup method properly on error

If the call to acpi_ds_init_aml_walk() fails, then we have to undo the
walk state push done by acpi_ds_create_walk_state(). Otherwise, the
new walk state (which has just been freed) will remain on the thread's
walk_state_list and be dereferenced in acpi_ps_parse_aml() when we try
to get the new state.

You can observe this when reading e.g.


Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
drivers/acpi/acpica/dsmethod.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/acpi/acpica/dsmethod.c
b/drivers/acpi/acpica/dsmethod.c index 47c7b52..44b50a6 100644
--- a/drivers/acpi/acpica/dsmethod.c
+++ b/drivers/acpi/acpica/dsmethod.c
@@ -596,6 +596,8 @@ cleanup:
/* On error, we must terminate the method properly */

acpi_ds_terminate_control_method(obj_desc, next_walk_state);
+ if (thread)
+ acpi_ds_pop_walk_state(thread);


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