Patchwork [V4] acpi: acpica: fix acpi parse and parseext cache leaks

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Submitter Seunghun Han
Date June 23, 2017, 9:36 a.m.
Message ID <1498210597-112293-1-git-send-email-kkamagui@gmail.com>
Download mbox | patch
Permalink /patch/9806085/
State Not Applicable, archived
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Seunghun Han - June 23, 2017, 9:36 a.m.
I'm Seunghun Han, and I work for National Security Research Institute of
South Korea.

I have been doing a research on ACPI and found an ACPI cache leak in ACPI
early abort cases.

Boot log of ACPI cache leak is as follows:
[    0.352414] ACPI: Added _OSI(Module Device)
[    0.353182] ACPI: Added _OSI(Processor Device)
[    0.353182] ACPI: Added _OSI(3.0 _SCP Extensions)
[    0.353182] ACPI: Added _OSI(Processor Aggregator Device)
[    0.356028] ACPI: Unable to start the ACPI Interpreter
[    0.356799] ACPI Error: Could not remove SCI handler (20170303/evmisc-281)
[    0.360215] kmem_cache_destroy Acpi-State: Slab cache still has objects
[    0.360648] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W
4.12.0-rc4-next-20170608+ #10
[    0.361273] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS
VirtualBox 12/01/2006
[    0.361873] Call Trace:
[    0.362243]  ? dump_stack+0x5c/0x81
[    0.362591]  ? kmem_cache_destroy+0x1aa/0x1c0
[    0.362944]  ? acpi_sleep_proc_init+0x27/0x27
[    0.363296]  ? acpi_os_delete_cache+0xa/0x10
[    0.363646]  ? acpi_ut_delete_caches+0x6d/0x7b
[    0.364000]  ? acpi_terminate+0xa/0x14
[    0.364000]  ? acpi_init+0x2af/0x34f
[    0.364000]  ? __class_create+0x4c/0x80
[    0.364000]  ? video_setup+0x7f/0x7f
[    0.364000]  ? acpi_sleep_proc_init+0x27/0x27
[    0.364000]  ? do_one_initcall+0x4e/0x1a0
[    0.364000]  ? kernel_init_freeable+0x189/0x20a
[    0.364000]  ? rest_init+0xc0/0xc0
[    0.364000]  ? kernel_init+0xa/0x100
[    0.364000]  ? ret_from_fork+0x25/0x30

I analyzed this memory leak in detail. I found that “Acpi-State” cache and
“Acpi-Parse” cache were merged because the size of cache objects was same
slab cache size.

I finally found “Acpi-Parse” cache and “Acpi-ParseExt” cache were leaked
using SLAB_NEVER_MERGE flag in kmem_cache_create() function.

Real ACPI cache leak point is as follows:
[    0.360101] ACPI: Added _OSI(Module Device)
[    0.360101] ACPI: Added _OSI(Processor Device)
[    0.360101] ACPI: Added _OSI(3.0 _SCP Extensions)
[    0.361043] ACPI: Added _OSI(Processor Aggregator Device)
[    0.364016] ACPI: Unable to start the ACPI Interpreter
[    0.365061] ACPI Error: Could not remove SCI handler (20170303/evmisc-281)
[    0.368174] kmem_cache_destroy Acpi-Parse: Slab cache still has objects
[    0.369332] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G        W
4.12.0-rc4-next-20170608+ #8
[    0.371256] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS
VirtualBox 12/01/2006
[    0.372000] Call Trace:
[    0.372000]  ? dump_stack+0x5c/0x81
[    0.372000]  ? kmem_cache_destroy+0x1aa/0x1c0
[    0.372000]  ? acpi_sleep_proc_init+0x27/0x27
[    0.372000]  ? acpi_os_delete_cache+0xa/0x10
[    0.372000]  ? acpi_ut_delete_caches+0x56/0x7b
[    0.372000]  ? acpi_terminate+0xa/0x14
[    0.372000]  ? acpi_init+0x2af/0x34f
[    0.372000]  ? __class_create+0x4c/0x80
[    0.372000]  ? video_setup+0x7f/0x7f
[    0.372000]  ? acpi_sleep_proc_init+0x27/0x27
[    0.372000]  ? do_one_initcall+0x4e/0x1a0
[    0.372000]  ? kernel_init_freeable+0x189/0x20a
[    0.372000]  ? rest_init+0xc0/0xc0
[    0.372000]  ? kernel_init+0xa/0x100
[    0.372000]  ? ret_from_fork+0x25/0x30
[    0.388039] kmem_cache_destroy Acpi-ParseExt: Slab cache still has objects
[    0.389063] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G        W
4.12.0-rc4-next-20170608+ #8
[    0.390557] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS
VirtualBox 12/01/2006
[    0.392000] Call Trace:
[    0.392000]  ? dump_stack+0x5c/0x81
[    0.392000]  ? kmem_cache_destroy+0x1aa/0x1c0
[    0.392000]  ? acpi_sleep_proc_init+0x27/0x27
[    0.392000]  ? acpi_os_delete_cache+0xa/0x10
[    0.392000]  ? acpi_ut_delete_caches+0x6d/0x7b
[    0.392000]  ? acpi_terminate+0xa/0x14
[    0.392000]  ? acpi_init+0x2af/0x34f
[    0.392000]  ? __class_create+0x4c/0x80
[    0.392000]  ? video_setup+0x7f/0x7f
[    0.392000]  ? acpi_sleep_proc_init+0x27/0x27
[    0.392000]  ? do_one_initcall+0x4e/0x1a0
[    0.392000]  ? kernel_init_freeable+0x189/0x20a
[    0.392000]  ? rest_init+0xc0/0xc0
[    0.392000]  ? kernel_init+0xa/0x100
[    0.392000]  ? ret_from_fork+0x25/0x30

When early abort is occurred due to invalid ACPI information, Linux kernel
terminates ACPI by calling acpi_terminate() function. The function calls
acpi_ut_delete_caches() function to delete local caches (acpi_gbl_namespace_
cache, state_cache, operand_cache, ps_node_cache, ps_node_ext_cache).

But the deletion codes in acpi_ut_delete_caches() function only delete
slab caches using kmem_cache_destroy() function, therefore the cache
objects should be flushed before acpi_ut_delete_caches() function.

“Acpi-Parse” cache and “Acpi-ParseExt” cache are used in an AML parse
function, acpi_ps_parse_loop(). The function should have flush codes to
handle an error state due to invalid AML codes.

This cache leak has a security threat because an old kernel (<= 4.9) shows
memory locations of kernel functions in stack dump. Some malicious users
could use this information to neutralize kernel ASLR.

To fix ACPI cache leak for enhancing security, I made a patch which has
flush codes in acpi_ps_parse_loop() function.

I hope that this patch improves the security of Linux kernel.

Thank you.

Signed-off-by: Seunghun Han <kkamagui@gmail.com>
---
Changes since v3: change control transfer according to reviewer's comments.
Changes since v2: merge flush code with existing code and change comments.
Changes since v1: move flush code to acpi_ps_complete_final_op() function.

 drivers/acpi/acpica/psobject.c | 53 +++++++++++++-----------------------------
 1 file changed, 16 insertions(+), 37 deletions(-)
Andy Shevchenko - June 25, 2017, 4:13 p.m.
On Fri, Jun 23, 2017 at 12:36 PM, Seunghun Han <kkamagui@gmail.com> wrote:
> I'm Seunghun Han, and I work for National Security Research Institute of
> South Korea.


> -                                       /* Clean up */
> -                                       do {
> -                                               if (op) {
> -                                                       status2 =
> -                                                           acpi_ps_complete_this_op
> -                                                           (walk_state, op);
> -                                                       if (ACPI_FAILURE
> -                                                           (status2)) {
> -                                                               return_ACPI_STATUS
> -                                                                   (status2);
> -                                                       }
> -                                               }
> -
> -                                               acpi_ps_pop_scope(&
> -                                                                 (walk_state->
> -                                                                  parser_state),
> -                                                                 &op,
> -                                                                 &walk_state->
> -                                                                 arg_types,
> -                                                                 &walk_state->
> -                                                                 arg_count);
> -
> -                                       } while (op);

I didn't get, do you send an incremental patch as a new version?!
Seunghun Han - June 26, 2017, 5:26 a.m.
Hello, Andy.

Thank you for your reply.

Patch V4 is the last patch which is applied all changes from original code.
Due to maintainer's advice, Patch V1, V2, V3 have reverted and I made
the latest patch, Patch V4.
(the review is here, https://github.com/acpica/acpica/pull/278)

Therefore, it seems that incremental patch is not needed.

If you have any request, please let me know.

Best regards.

ps) I am sending email again after removing HTML part.

2017-06-26 7:12 GMT+09:00 Seunghun Han <kkamagui@gmail.com>:
> Hello, Andy.
>
> Thank you for your reply.
>
> Patch V4 is the last patch which is applied all changes from original code.
> Due to reviewer's advice, Patch V1, V2, V3 has reverted and I made the
> latest patch, Patch V4.
> Therefore, it seems that incremental patch is not needed.
>
> If you have any requests, please let me know.
>
> Best regards.
>
>
> 2017년 6월 26일 (월) 오전 1:13, Andy Shevchenko <andy.shevchenko@gmail.com>님이 작성:
>>
>> On Fri, Jun 23, 2017 at 12:36 PM, Seunghun Han <kkamagui@gmail.com> wrote:
>> > I'm Seunghun Han, and I work for National Security Research Institute of
>> > South Korea.
>>
>>
>> > -                                       /* Clean up */
>> > -                                       do {
>> > -                                               if (op) {
>> > -                                                       status2 =
>> > -
>> > acpi_ps_complete_this_op
>> > -                                                           (walk_state,
>> > op);
>> > -                                                       if (ACPI_FAILURE
>> > -                                                           (status2)) {
>> > -
>> > return_ACPI_STATUS
>> > -
>> > (status2);
>> > -                                                       }
>> > -                                               }
>> > -
>> > -                                               acpi_ps_pop_scope(&
>> > -
>> > (walk_state->
>> > -
>> > parser_state),
>> > -                                                                 &op,
>> > -
>> > &walk_state->
>> > -
>> > arg_types,
>> > -
>> > &walk_state->
>> > -
>> > arg_count);
>> > -
>> > -                                       } while (op);
>>
>> I didn't get, do you send an incremental patch as a new version?!
>>
>> --
>> With Best Regards,
>> Andy Shevchenko
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Patch

diff --git a/drivers/acpi/acpica/psobject.c b/drivers/acpi/acpica/psobject.c
index 5bcb618..4539391 100644
--- a/drivers/acpi/acpica/psobject.c
+++ b/drivers/acpi/acpica/psobject.c
@@ -608,7 +608,8 @@  acpi_status
 acpi_ps_complete_final_op(struct acpi_walk_state *walk_state,
 			  union acpi_parse_object *op, acpi_status status)
 {
-	acpi_status status2;
+	acpi_status return_status = AE_OK;
+	u8 ascending = TRUE;
 
 	ACPI_FUNCTION_TRACE_PTR(ps_complete_final_op, walk_state);
 
@@ -622,7 +623,8 @@  acpi_ps_complete_final_op(struct acpi_walk_state *walk_state,
 			  op));
 	do {
 		if (op) {
-			if (walk_state->ascending_callback != NULL) {
+			if (ascending &&
+			    walk_state->ascending_callback != NULL) {
 				walk_state->op = op;
 				walk_state->op_info =
 				    acpi_ps_get_opcode_info(op->common.
@@ -644,49 +646,26 @@  acpi_ps_complete_final_op(struct acpi_walk_state *walk_state,
 				}
 
 				if (status == AE_CTRL_TERMINATE) {
-					status = AE_OK;
-
-					/* Clean up */
-					do {
-						if (op) {
-							status2 =
-							    acpi_ps_complete_this_op
-							    (walk_state, op);
-							if (ACPI_FAILURE
-							    (status2)) {
-								return_ACPI_STATUS
-								    (status2);
-							}
-						}
-
-						acpi_ps_pop_scope(&
-								  (walk_state->
-								   parser_state),
-								  &op,
-								  &walk_state->
-								  arg_types,
-								  &walk_state->
-								  arg_count);
-
-					} while (op);
-
-					return_ACPI_STATUS(status);
+					ascending = FALSE;
+					return_status = AE_CTRL_TERMINATE;
 				}
 
 				else if (ACPI_FAILURE(status)) {
 
 					/* First error is most important */
 
-					(void)
-					    acpi_ps_complete_this_op(walk_state,
-								     op);
-					return_ACPI_STATUS(status);
+					ascending = FALSE;
+					return_status = status;
 				}
 			}
 
-			status2 = acpi_ps_complete_this_op(walk_state, op);
-			if (ACPI_FAILURE(status2)) {
-				return_ACPI_STATUS(status2);
+			status = acpi_ps_complete_this_op(walk_state, op);
+			if (ACPI_FAILURE(status)) {
+				ascending = FALSE;
+				if (ACPI_SUCCESS(return_status) ||
+				    return_status == AE_CTRL_TERMINATE) {
+					return_status = status;
+				}
 			}
 		}
 
@@ -696,5 +675,5 @@  acpi_ps_complete_final_op(struct acpi_walk_state *walk_state,
 
 	} while (op);
 
-	return_ACPI_STATUS(status);
+	return_ACPI_STATUS(return_status);
 }